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Search: a053602 -id:a053602
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Number of incongruent ways to tile a 3 X 2n room with 1x2 Tatami mats. At most 3 Tatami mats may meet at a point.
+10
7
2, 2, 2, 4, 5, 9, 12, 21, 30, 51, 76, 127, 195, 322, 504, 826, 1309, 2135, 3410, 5545, 8900, 14445, 23256, 37701, 60813, 98514, 159094, 257608, 416325, 673933, 1089648, 1763581, 2852242, 4615823, 7466468, 12082291, 19546175, 31628466
OFFSET
1,1
FORMULA
For n >= 8, a(n) = a(n-1) + 2*a(n-2) - a(n-3) - a(n-5) - a(n-6).
O.g.f.: x(2-4x^2-x^4+x^6)/((1-x-x^2)(1-x^2-x^4)). a(n) = (A000045(n+1)+A053602(n+1))/2, n>1. [From R. J. Mathar, Aug 30 2008]
CROSSREFS
Cf. A068922 for total number of tilings, A068926 for more info.
Essentially the same as A001224.
KEYWORD
easy,nonn
AUTHOR
Dean Hickerson, Mar 11 2002
STATUS
approved
a(n) = (-1)^(n-1)*(a(n-1) - a(n-2)), a(1)=1, a(2)=1.
+10
6
1, 1, 0, 1, 1, 0, -1, 1, 2, -1, -3, 2, 5, -3, -8, 5, 13, -8, -21, 13, 34, -21, -55, 34, 89, -55, -144, 89, 233, -144, -377, 233, 610, -377, -987, 610, 1597, -987, -2584, 1597, 4181, -2584, -6765, 4181, 10946, -6765, -17711, 10946, 28657, -17711, -46368
OFFSET
1,9
FORMULA
a(3-n) = A053602(n).
From Michael Somos: (Start)
G.f.: x*(1 + x + x^2 + 2*x^3)/(1 + x^2 - x^4).
a(n) = -a(n-2) + a(n-4). (End)
a(n) = b(n-1) + b(n-2) + b(n-3) + 2*b(n-4), where b(n) = i^n * A079977(n). - G. C. Greubel, Dec 06 2022
MATHEMATICA
LinearRecurrence[{0, -1, 0, 1}, {1, 1, 0, 1}, 60] (* Harvey P. Dale, May 08 2017 *)
PROG
(PARI) a(n)=fibonacci((3-n)\2+(3-n)%2*2)
(Sage)
def A051792():
x, y, b = 1, 1, true
while True:
yield x
x, y = y, x - y
y = -y if b else y
b = not b
a = A051792()
print([next(a) for _ in range(51)]) # Peter Luschny, Mar 19 2020
(Magma) [Fibonacci(1 -Floor((n-4)/2) -2*((n-4) mod 2)): n in [1..60]]; // G. C. Greubel, Dec 06 2022
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Dec 10 1999
STATUS
approved
Row sums of A123230.
+10
4
1, 2, 1, 3, 2, 5, 3, 8, 5, 13, 8, 21, 13, 34, 21, 55, 34, 89, 55, 144, 89, 233, 144, 377, 233, 610, 377, 987, 610, 1597, 987, 2584, 1597, 4181, 2584, 6765, 4181, 10946, 6765, 17711, 10946, 28657, 17711, 46368, 28657, 75025, 46368, 121393, 75025, 196418
OFFSET
1,2
COMMENTS
All terms are Fibonacci numbers A000045: a(2n-1) = Fibonacci(n), a(2n) = Fibonacci(n+2), a(2n-1) = a(2n+2). - Alexander Adamchuk, Oct 08 2006
FORMULA
From Alexander Adamchuk, Oct 08 2006: (Start)
a(n) = Fibonacci(A028242(n+2)).
a(n) = Fibonacci(A030451(n+1)).
a(n) = Fibonacci(3/4 -(-1)^(n+1)*3/4 +(n+1)/2). (End)
a(n) = A053602(n+1) = A097594(n-5). - R. J. Mathar, Mar 08 2011
G.f. -x*(1+2*x+x^3) / ( -1+x^2+x^4 ). - R. J. Mathar, Mar 08 2011
a(n) = a(n-2) + a(n-4). - Muniru A Asiru, Oct 12 2018
MAPLE
seq(coeff(series(-x*(1+2*x+x^3)/(x^4+x^2-1), x, n+1), x, n), n = 1 .. 50); # Muniru A Asiru, Oct 12 2018
MATHEMATICA
p[0, x] = 1; p[1, x] = x + 1; p[k_, x_] := p[k, x] = x*p[k - 1, x] + (-1)^(n + 1)p[k - 2, x]; Table[Sum[CoefficientList[p[n, x], x][[m]], {m, 1, n + 1}], {n, 0, 20}]
Rest[Flatten[Reverse/@Partition[Fibonacci[Range[30]], 2, 1]]] (* Harvey P. Dale, Mar 19 2013 *)
PROG
(PARI) vector(50, n, fibonacci(3/4 -(-1)^(n+1)*3/4 +(n+1)/2)) \\ G. C. Greubel, Oct 12 2018
(Magma) m:=50; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(x*(1 + 2*x + x^3)/(1 - x^2 - x^4))); // G. C. Greubel, Oct 12 2018
(GAP) a:=[1, 2, 1, 3];; for n in [5..50] do a[n]:=a[n-2]+a[n-4]; od; a; # Muniru A Asiru, Oct 12 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Oct 06 2006
EXTENSIONS
More terms from Alexander Adamchuk, Oct 08 2006
STATUS
approved
Triangle read by rows: T(n,k) = number of palindromic compositions of n in which the largest part is equal to k, 1 <= k <= n.
+10
4
1, 1, 1, 1, 0, 1, 1, 2, 0, 1, 1, 1, 1, 0, 1, 1, 4, 1, 1, 0, 1, 1, 2, 3, 0, 1, 0, 1, 1, 7, 3, 3, 0, 1, 0, 1, 1, 4, 6, 1, 2, 0, 1, 0, 1, 1, 12, 7, 7, 1, 2, 0, 1, 0, 1, 1, 7, 12, 3, 5, 0, 2, 0, 1, 0, 1, 1, 20, 16, 15, 3, 5, 0, 2, 0, 1, 0, 1
OFFSET
1,8
COMMENTS
A palindromic composition of a natural number m is an ordered partition of m into N+1 natural numbers (or parts), p_0, p_1, ..., p_N, of the form m = p_0 + p_1 + ... + p_N such that p_j = p_{N-j}, for each j in {0,...,N}. Two palindromic compositions, sum_{j=0..N} p_j and sum_{j=0..N} q_j (say), are identical if and only if p_j = q_j, j = 0,...,N; otherwise they are taken to be distinct.
LINKS
Alois P. Heinz, Rows n = 1..141, flattened (rows n = 1..50 from Charles R Greathouse IV)
V. E. Hoggatt, Jr., and Marjorie Bicknell, Palindromic compositions, Fibonacci Quart., Vol. 13(4), 1975, pp. 350-356.
EXAMPLE
There are eight palindromic compositions of n=7, namely, {7}, {3,1,3}, {2,3,2}, {2,1,1,1,2}, {1,5,1}, {1,2,1,2,1}, {1,1,3,1,1}, {1,1,1,1,1,1,1}, and three of them have the largest part equal to 3, so T(7,3) = 3.
Triangle T(n,k) begins:
1;
1, 1;
1, 0, 1,
1, 2, 0, 1;
1, 1, 1, 0, 1;
1, 4, 1, 1, 0, 1;
1, 2, 3, 0, 1, 0, 1;
1, 7, 3, 3, 0, 1, 0, 1;
1, 4, 6, 1, 2, 0, 1, 0, 1;
1, 12, 7, 7, 1, 2, 0, 1, 0, 1;
...
MAPLE
b:= proc(n, k) option remember; `if`(n<=k, 1, 0)+
add(b(n-2*j, k), j=1..min(k, iquo(n, 2)))
end:
T:= (n, k)-> b(n, k) -b(n, k-1):
seq(seq(T(n, k), k=1..n), n=1..14); # Alois P. Heinz, Dec 11 2013
MATHEMATICA
b[n_, k_] := b[n, k] = If[n <= k, 1, 0] + Sum[b[n-2*j, k], { j, 1, Min[k, Quotient[n, 2]]}]; t[n_, k_] := b[n, k] - b[n, k-1]; Table[Table[t[n, k], {k, 1, n}], {n, 1, 14}] // Flatten (* Jean-François Alcover, Dec 13 2013, translated from Alois P. Heinz's Maple code *)
PROG
(PARI) T(n, k, ok=0)={
if(n<1, return(n==0 && ok));
if(k>n/2 && !ok,
n-=k;
if(n<0||n%2, return(0));
return(2^max(n/2-1, 0))
);
sum(i=1, k,
T(n-2*i, k, ok||i==k)
)+(n==k || (ok && n<k))
}; \\ Charles R Greathouse IV, Dec 11 2013
CROSSREFS
Cf. A016116 (row sums), A233324 (row partial sums).
T(n,2)+1 = A053602(n+1) = A123231(n). T(4n-2,2n) = A011782(n-1). - Alois P. Heinz, Dec 11 2013
KEYWORD
nonn,tabl
AUTHOR
L. Edson Jeffery, Dec 10 2013
STATUS
approved
Triangle read by rows: T(n,k) = number of palindromic compositions of n in which no part exceeds k, 1 <= k <= n.
+10
4
1, 1, 2, 1, 1, 2, 1, 3, 3, 4, 1, 2, 3, 3, 4, 1, 5, 6, 7, 7, 8, 1, 3, 6, 6, 7, 7, 8, 1, 8, 11, 14, 14, 15, 15, 16, 1, 5, 11, 12, 14, 14, 15, 15, 16, 1, 13, 20, 27, 28, 30, 30, 31, 31, 32, 1, 8, 20, 23, 28, 28, 30, 30, 31, 31, 32, 1, 21, 37, 52, 55, 60, 60, 62, 62, 63, 63, 64
OFFSET
1,3
COMMENTS
A palindromic composition of a natural number m is an ordered partition of m into N+1 natural numbers (or parts), p_0, p_1, ..., p_N, of the form m = p_0 + p_1 + ... + p_N such that p_j = p_{N-j}, for each j in {0,...,N}. Two palindromic compositions, sum_{j=0..N} p_j and sum_{j=0..N} q_j (say), are identical if and only if p_j = q_j, j = 0,...,N; otherwise they are taken to be distinct.
Partial sums of rows of A233323.
T(n,k) is defined for n,k >= 0. T(n,k) = T(n,n) = A016116(n) for k>= 0. - Alois P. Heinz, Dec 11 2013
LINKS
V. E. Hoggatt, Jr., and Marjorie Bicknell, Palindromic compositions, Fibonacci Quart., Vol. 13(4), 1975, pp. 350-356.
EXAMPLE
Triangle T(n,k) begins:
1;
1, 2;
1, 1, 2;
1, 3, 3, 4;
1, 2, 3, 3, 4;
1, 5, 6, 7, 7, 8;
1, 3, 6, 6, 7, 7, 8;
1, 8, 11, 14, 14, 15, 15, 16;
1, 5, 11, 12, 14, 14, 15, 15, 16;
1, 13, 20, 27, 28, 30, 30, 31, 31, 32;
MAPLE
T:= proc(n, k) option remember; `if`(n<=k, 1, 0)+
add(T(n-2*j, k), j=1..min(k, iquo(n, 2)))
end:
seq(seq(T(n, k), k=1..n), n=1..14); # Alois P. Heinz, Dec 11 2013
MATHEMATICA
T[n_, k_] := T[n, k] = If[n <= k, 1, 0] + Sum[T[n-2*j, k], {j, 1, Min[k, Quotient[ n, 2]]}]; Table[Table[T[n, k], {k, 1, n}], {n, 1, 14}] // Flatten (* Jean-François Alcover, Mar 09 2015, after Alois P. Heinz *)
PROG
(PARI) T(n, k)=if(n<1, return(n==0)); sum(i=1, k, T(n-2*i, k))+(n<=k) \\ Charles R Greathouse IV, Dec 11 2013
CROSSREFS
Cf. A233323.
T(n,2) = A053602(n+1) = A123231(n). T(2n,3) = A001590(n+3). T(2n,4) = A001631(n+4). - Alois P. Heinz, Dec 11 2013
KEYWORD
nonn,tabl
AUTHOR
L. Edson Jeffery, Dec 11 2013
STATUS
approved
"BHK" (reversible, identity, unlabeled) transform of 1,0,1,0...(odds).
+10
2
1, 0, 1, 1, 2, 3, 5, 9, 14, 25, 39, 68, 107, 182, 289, 483, 772, 1275, 2047, 3355, 5402, 8811, 14213, 23112, 37325, 60580, 97905, 158717, 256622, 415715, 672337, 1088661, 1760998, 2850645, 4611643, 7463884, 12075527, 19541994
OFFSET
1,5
FORMULA
G.f.: x*(1-x-2*x^2+2*x^3+x^6)/((1-x)*(1+x)*(1-x-x^2)*(1-x^2-x^4)).
a(n) = a(n-1) + 3*a(n-2) - 2*a(n-3) - 2*a(n-4) - a(n-6) + a(n-7) + a(n-8) for n > 8. - Andrew Howroyd, Aug 31 2018
2*a(n) = 2*A000035(n) + A000045(n) - A053602(n). - R. J. Mathar, Mar 02 2022
PROG
(PARI) Vec((1-x-2*x^2+2*x^3+x^6)/((1-x)*(1+x)*(1-x-x^2)*(1-x^2-x^4)) + O(x^40)) \\ Andrew Howroyd, Aug 31 2018
KEYWORD
nonn,easy
STATUS
approved
a(n) = (a(n-1) mod a(n-2)) + a(n-2), a(0) = 3, a(1) = 2.
+10
2
2, 5, 3, 8, 5, 13, 8, 21, 13, 34, 21, 55, 34, 89, 55, 144, 89, 233, 144, 377, 233, 610, 377, 987, 610, 1597, 987, 2584, 1597, 4181, 2584, 6765, 4181, 10946, 6765, 17711, 10946, 28657, 17711, 46368, 28657, 75025, 46368, 121393, 75025, 196418, 121393, 317811, 196418, 514229, 317811, 832040, 514229
OFFSET
0,1
FORMULA
a(2n) = Fibonacci(n+4), a(2n+1) = Fibonacci(n+3).
a(n) = A053602(n+6).
a(n) = abs( A051792(n+11) ).
G.f.: (2 + 5*x + x^2 + 3*x^3)/(1 - x^2 - x^4). - G. C. Greubel, Dec 06 2022
MATHEMATICA
LinearRecurrence[{0, 1, 0, 1}, {2, 5, 3, 8}, 60] (* G. C. Greubel, Dec 06 2022 *)
PROG
(Magma) [Fibonacci(3 +Floor(n/2) +2*(n mod 2)): n in [0..60]]; // G. C. Greubel, Dec 06 2022
(SageMath) [fibonacci(3 +(n//2) + 2*(n%2)) for n in range(61)] # G. C. Greubel, Dec 06 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Gerald McGarvey, Aug 29 2004
STATUS
approved
Difference sequence of the sequence A116470 of all distinct Fibonacci numbers and Lucas numbers (A000032).
+10
2
1, 1, 1, 1, 2, 1, 3, 2, 5, 3, 8, 5, 13, 8, 21, 13, 34, 21, 55, 34, 89, 55, 144, 89, 233, 144, 377, 233, 610, 377, 987, 610, 1597, 987, 2584, 1597, 4181, 2584, 6765, 4181, 10946, 6765, 17711, 10946, 28657, 17711, 46368, 28657, 75025, 46368, 121393, 75025
OFFSET
1,5
COMMENTS
Every term is a Fibonacci number (A000045).
FORMULA
From Colin Barker, May 10 2016: (Start)
a(n) = a(n-2)+a(n-4) for n>4.
G.f.: x*(1+x-x^5) / (1-x^2-x^4).
(End)
a(n) = A053602(n-2), n>2. - R. J. Mathar, May 20 2016
a(n) = A123231(n-3), n>3. - Georg Fischer, Oct 23 2018
EXAMPLE
A116470 = (1, 2, 3, 4, 5, 7, 8, 11, 13, 18, 21, 29, 34, 47, 55, 76,...), so that (a(n)) = (1,1,1,1,2,1,3,2,5,3,8,5,13,8,12,...).
MATHEMATICA
u = Table[Fibonacci[n], {n, 1, 200}]; v = Table[LucasL[n], {n, 1, 200}];
Take[Differences[Union[u, v]], 100]
PROG
(PARI) Vec(x*(1+x-x^5)/(1-x^2-x^4) + O(x^50)) \\ Colin Barker, May 10 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, May 10 2016
STATUS
approved
Triangular array read by rows: T(n,k) is the number of palindromic compositions of n having exactly k 1's, n>=0, 0<=k<=n.
+10
1
1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 2, 0, 1, 0, 1, 1, 1, 1, 0, 0, 1, 3, 0, 3, 0, 1, 0, 1, 2, 1, 1, 2, 1, 0, 0, 1, 5, 0, 5, 0, 4, 0, 1, 0, 1, 3, 2, 3, 2, 1, 3, 1, 0, 0, 1, 8, 0, 10, 0, 7, 0, 5, 0, 1, 0, 1, 5, 3, 5, 5, 4, 3, 1, 4, 1, 0, 0, 1, 13, 0, 18, 0, 16, 0, 9, 0, 6, 0, 1, 0, 1, 8, 5, 10, 8, 7, 9, 5, 4, 1, 5, 1, 0, 0, 1
OFFSET
0,11
COMMENTS
Row sums = 2^floor(n/2).
T(n,0) = A053602(n-1) for n>0, T(n,1) = A079977(n-5) for n>4, T(2n+1,3) = A006367(n-1) for n>0, both bisections of column k=2 contain A010049. - Alois P. Heinz, Mar 21 2014
LINKS
FORMULA
G.f.: G(x,y) = ((1 + x)*(1 - x + x^2 + x*y - x^2*y))/(1 - x^2 - x^4 - x^2*y^2 + x^4*y^2). Satisfies G(x,y) = 1/(1 - x) - x + y*x + (x^2/(1 - x^2) - x^2 +y^2*x^2)*G(x,y).
EXAMPLE
1,
0, 1,
1, 0, 1,
1, 0, 0, 1,
2, 0, 1, 0, 1,
1, 1, 1, 0, 0, 1,
3, 0, 3, 0, 1, 0, 1,
2, 1, 1, 2, 1, 0, 0, 1,
5, 0, 5, 0, 4, 0, 1, 0, 1,
3, 2, 3, 2, 1, 3, 1, 0, 0, 1
There are eight palindromic compositions of 6: T(6,0)=3 because we have: 6, 3+3, 2+2+2. T(6,2)=3 because we have: 1+4+1, 2+1+1+2, 1+2+2+1. T(6,4)=1 because we have: 1+1+2+1+1. T(6,6)=1 because we have: 1+1+1+1+1+1.
MAPLE
b:= proc(n) option remember; `if`(n=0, 1, expand(
add(b(n-j)*`if`(j=1, x^2, 1), j=1..n)))
end:
T:= n-> (p-> seq(coeff(p, x, i), i=0..n))
(add(b(i)*`if`(n-2*i=1, x, 1), i=0..n/2)):
seq(T(n), n=0..30); # Alois P. Heinz, Mar 21 2014
MATHEMATICA
nn=15; Table[Take[CoefficientList[Series[((1+x)*(1-x+x^2+x*y-x^2*y))/(1-x^2-x^4-x^2*y^2+x^4*y^2), {x, 0, nn}], {x, y}][[n]], n], {n, 1, nn}]//Grid
KEYWORD
nonn,tabl
AUTHOR
Geoffrey Critzer, Mar 20 2014
STATUS
approved
Triangle read by rows: T(n,k) is the number of 00-avoiding binary words of length n having degree of asymmetry equal to k (n>=0; 0<=k<=floor(n/2)).
+10
1
1, 2, 1, 2, 3, 2, 2, 4, 2, 5, 6, 2, 3, 8, 8, 2, 8, 14, 10, 2, 5, 16, 20, 12, 2, 13, 30, 30, 14, 2, 8, 30, 48, 40, 16, 2, 21, 60, 78, 54, 18, 2, 13, 56, 106, 112, 68, 20, 2, 34, 116, 184, 166, 86, 22, 2, 21, 102, 224, 286, 224, 104, 24, 2, 55, 218, 408, 452, 310, 126, 26, 2
OFFSET
0,2
COMMENTS
The degree of asymmetry of a finite sequence of numbers is defined to be the number of pairs of symmetrically positioned distinct entries. Example: the degree of asymmetry of (2,7,6,4,5,7,3) is 2, counting the pairs (2,3) and (6,5).
A sequence is palindromic if and only if its degree of asymmetry is 0.
Number of entries in row n is 1+floor(n/2).
Sum of entries in row n is A000045(n+2) (Fibonacci).
T(n,0) = A053602(n+2) (= number of palindromic 00-avoiding binary words of length n).
Sum(k*T(n,k), k>=0) = A275436(n).
FORMULA
G.f.: G(t,z) = (1 + 2z + tz^2 +z^3 -tz^5)/(1 - z^2 - tz^2 - z^4 - tz^4 + tz^6).
EXAMPLE
Row 3 is [3,2] because the 00-avoiding binary words of length 3 are 010, 011, 101, 110, 111, having asymmetry degrees 0, 1, 0, 1, 0, respectively.
Triangle starts:
1;
2;
1,2;
3,2;
2,4,2;
5,6,2.
MAPLE
G := (1+2*z+t*z^2+z^3-t*z^5)/(1-z^2-t*z^2-z^4-t*z^4+t*z^6): Gser := simplify(series(G, z = 0, 20)): for n from 0 to 18 do P[n] := sort(coeff(Gser, z, n)) end do: for n from 0 to 18 do seq(coeff(P[n], t, j), j = 0 .. (1/2)*n) end do; # yields sequence in triangular form
MATHEMATICA
Table[BinCounts[#, {0, Floor[n/2] + 1, 1}] &@ Map[Total@ BitXor[Take[#, Ceiling[Length[#]/2]], Reverse@ Take[#, -Ceiling[Length[#]/2]]] &, Select[PadLeft[IntegerDigits[#, 2], n] & /@ Range[0, 2^n - 1], Length@ SequenceCases[#, {0, 0}] == 0 &]], {n, 0, 15}] // Flatten (* Michael De Vlieger, Aug 15 2016, Version 10.1 *)
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Emeric Deutsch, Aug 15 2016
STATUS
approved

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