Displaying 1-10 of 12 results found.
R(k), the minimal alternating Fibonacci representation of k, concatenated for k = 0, 1, 2,....
+10
15
0, 1, 2, 3, 5, -1, 5, 8, -2, 8, -1, 8, 13, -5, 1, 13, -3, 13, -2, 13, -1, 13, 21, -8, 1, 21, -8, 2, 21, -5, 21, -5, 1, 21, -3, 21, -2, 21, -1, 21, 34, -13, 1, 34, -13, 2, 34, -13, 3, 34, -13, 5, -1, 34, -8, 34, -8, 1, 34, -8, 2, 34, -5, 34, -5, 1, 34, -3, 34
COMMENTS
Suppose that b = (b(0), b(1), ... ) is an increasing sequence of positive integers satisfying b(0) = 1 and b(n+1) <= 2*b(n) for n >= 0. Let B(n) be the least b(m) >= n. Let R(0) = 1, and for n > 0, let R(n) = B(n) - R(B(n) - n). The resulting sum of the form R(n) = B(n) - B(m(1)) + B(m(2)) - ... + ((-1)^k)*B(k) is introduced here as the minimal alternating b-representation of n. The sum B(n) + B(m(2)) + ... we call the positive part of R(n), and the sum B(m(1)) + B(m(3)) + ... , the nonpositive part of R(n). The number ((-1)^k)*B(k) is the trace of n.
If b(n) = F(n+2), where F = A000045, then the sum is the minimal alternating Fibonacci-representation of n.
FORMULA
R(F(k)^2) = F(2k-1) - F(2k-3) + F(2k-5) - ... + d*F(5) + (-1)^k, where d = (-1)^(k+1).
EXAMPLE
R(0) = 0
R(1) = 1
R(2) = 2
R(3) = 3
R(4) = 5 - 1
R(9) = 13 - 5 + 1
R(25) = 34 - 13 + 5 - 1
R(64) = 89 - 34 + 13 - 5 + 1
MATHEMATICA
f[n_] = Fibonacci[n]; ff = Table[f[n], {n, 1, 70}];
s[n_] := Table[f[n + 2], {k, 1, f[n]}];
h[0] = {1}; h[n_] := Join[h[n - 1], s[n]];
g = h[12]; r[0] = {0};
r[n_] := If[MemberQ[ff, n], {n}, Join[{g[[n]]}, -r[g[[n]] - n]]];
Flatten[Table[r[n], {n, 0, 60}]]
CROSSREFS
Cf. A000045, A255973 (trace), A256656 (numbers with positive trace), A256657 (numbers with nonpositive trace), A256663 (positive part of R(n)), A256664 (nonpositive part of R(n)), A256654, A256696 (minimal alternating binary representations), A255974 (minimal alternating triangular-number representations), A256789 (minimal alternating squares representations).
R(k), the minimal alternating triangular-number representation of k, concatenated for k = 0, 1, 2,....
+10
10
0, 1, 3, -1, 3, 6, -3, 1, 6, -1, 6, 10, -3, 10, -3, 1, 10, -1, 10, 15, -6, 3, -1, 15, -3, 15, -3, 1, 15, -1, 15, 21, -6, 1, 21, -6, 3, -1, 21, -3, 21, -3, 1, 21, -1, 21, 28, -6, 28, -6, 1, 28, -6, 3, -1, 28, -3, 28, -3, 1, 28, -1, 28, 36, -10, 3, 36, -6, 36
COMMENTS
Suppose that b = (b(0), b(1), ... ) is an increasing sequence of positive integers satisfying b(0) = 1 and b(n+1) <= 2*b(n) for n >= 0. Let B(n) be the least b(m) >= n. Let R(0) = 1, and for n > 0, let R(n) = B(n) - R(B(n) - n). The resulting sum of the form R(n) = B(n) - B(m(1)) + B(m(2)) - ... + ((-1)^k)*B(k) is the minimal alternating b-representation of n. The sum B(n) + B(m(2)) + ... is the positive part of R(n), and the sum B(m(1)) + B(m(3)) + ... , the nonpositive part of R(n). The number ((-1)^k)*B(k) is the trace of n. If b(n) = n(n+1)/2, the n-th triangular number, then the sum R(n) is the minimal alternating triangular-number representation of n.
EXAMPLE
R(0) = 0
R(1) = 1
R(2) = 3 - 1
R(3) = 3
R(4) = 6 - 3 + 1
R(5) = 6 - 1
R(8) = 10 - 3 + 1
R(11) = 15 - 6 + 3 - 1
MATHEMATICA
b[n_] := n (n + 1)/2; bb = Table[b[n], {n, 0, 1000}];
s[n_] := Table[b[n], {k, 1, n}];
h[1] = {1}; h[n_] := Join[h[n - 1], s[n]];
g = h[100]; r[0] = {0};
r[n_] := If[MemberQ[bb, n], {n}, Join[{g[[n]]}, -r[g[[n]] - n]]]
t = Table[r[n], {n, 0, 120}] (* A255974 actual representations *)
Enhanced squares representations for k = 0, 1, 2, ..., concatenated.
+10
9
0, 1, 2, 3, 4, 4, 1, 4, 2, 4, 3, 4, 3, 1, 9, 9, 1, 9, 2, 9, 3, 9, 4, 9, 4, 1, 9, 4, 2, 16, 16, 1, 16, 2, 16, 3, 16, 4, 16, 4, 1, 16, 4, 2, 16, 4, 3, 16, 4, 3, 1, 25, 25, 1, 25, 2, 25, 3, 25, 4, 25, 4, 1, 25, 4, 2, 25, 4, 3, 25, 4, 3, 1, 25, 9, 25, 9, 1, 36
COMMENTS
Let B = {0,1,2,3,4,9,16,25,...}, so that B consists of the squares together with 2 and 3. We call B the enhanced basis of squares. Define R(0) = 0 and R(n) = g(n) + R(n - g(n)) for n > 0, where g(n) is the greatest number in B that is <= n. Thus, each n has an enhanced squares representation of the form R(n) = b(m(n)) + b(m(n-1)) + ... + b(m(k)), where b(n) > m(n-1) > ... > m(k) > 0, in which the last term, b(m(k)), is the trace.
The least n for which R(n) has 5 terms is given by R(168) = 144 + 16 + 4 + 3 + 1.
The least n for which R(n) has 6 terms is given by R(7224) = 7056 + 144 + 16 + 4 + 3 + 1.
EXAMPLE
R(0) = 0
R(1) = 1
R(2) = 2
R(3) = 3
R(4) = 4
R(8) = 4 + 3 + 1
R(24) = 16 + 4 + 3 + 1
MATHEMATICA
b[n_] := n^2; bb = Insert[Table[b[n], {n, 0, 100}] , 2, 3];
s[n_] := Table[b[n], {k, 1, 2 n + 1}];
h[1] = {0, 1, 2, 3}; h[n_] := Join[h[n - 1], s[n]];
g = h[100]; Take[g, 100]
r[0] = {0}; r[1] = {1}; r[2] = {2}; r[3] = {3}; r[8] = {4, 3, 1};
r[n_] := If[MemberQ[bb, n], {n}, Join[{g[[n]]}, r[n - g[[n]]]]];
t = Table[r[n], {n, 0, 120}] (* A256913, before concatenation *) Table[Last[r[n]], {n, 0, 120}] (* A256914 *) Table[Length[r[n]], {n, 0, 200}] (* A256915 *)
PROG
(Haskell)
a256913 n k = a256913_tabf !! n !! k
a256913_row n = a256913_tabf !! n
a256913_tabf = [0] : tail esr where
esr = (map r [0..8]) ++
f 9 (map fromInteger $ drop 3 a000290_list) where
f x gs@(g:hs@(h:_))
| x < h = (g : genericIndex esr (x - g)) : f (x + 1) gs
| otherwise = f x hs
r 0 = []; r 8 = [4, 3, 1]
r x = q : r (x - q) where q = [0, 1, 2, 3, 4, 4, 4, 4, 4] !! x
Trace of n in the minimal alternating squares representation of n.
+10
7
0, 1, -2, -1, 4, -4, 1, 2, -1, 9, -1, 4, -4, 1, 2, -1, 16, 1, -2, -1, 4, -4, 1, 2, -1, 25, 1, -9, 1, -2, -1, 4, -4, 1, 2, -1, 36, 4, -4, 1, -9, 1, -2, -1, 4, -4, 1, 2, -1, 49, -2, -1, 4, -4, 1, -9, 1, -2, -1, 4, -4, 1, 2, -1, 64, -16, 1, -2, -1, 4, -4, 1, -9
COMMENTS
For each positive integer m, the list of 2m numbers between m^2 and (m+1)^2 is repeated between (m+1)^2 and (m+2)^2. Consequently, a limiting sequence is formed by reversing the repeated lists. The limiting sequence is -1, 2, 1, -4, 4, -1, -2, 1, -9, 1, -4, 4, -1, -2, 1, -16, ...
EXAMPLE
R(0) = 0, so a(0) = 0;
R(1) = 1, so a(1) = 1;
R(2) = 4 - 2, so a(2) = -2;
R(7) = 9 - 4 + 2, so a(7) = 2;
R(89) = 100 - 16 + 9 - 4, so a(89) = -4.
MATHEMATICA
b[n_] := n^2; bb = Table[b[n], {n, 0, 1000}];
s[n_] := Table[b[n], {k, 1, 2 n - 1}];
h[1] = {1}; h[n_] := Join[h[n - 1], s[n]];
g = h[100]; r[0] = {0}; r[1] = {1}; r[2] = {4, -2};
r[n_] := If[MemberQ[bb, n], {n}, Join[{g[[n]]}, -r[g[[n]] - n]]];
Table[r[n], {n, 0, 120}] (* A256789 *) Flatten[Table[Last[r[n]], {n, 0, 100}]] (* A256791 *)
Numbers whose minimal alternating squares representation has positive trace.
+10
4
1, 4, 6, 7, 9, 11, 13, 14, 16, 17, 20, 22, 23, 25, 26, 28, 31, 33, 34, 36, 37, 39, 41, 44, 46, 47, 49, 52, 54, 56, 59, 61, 62, 64, 66, 69, 71, 73, 76, 78, 79, 81, 82, 85, 88, 90, 92, 95, 97, 98, 100, 102, 103, 106, 109, 111, 113, 116, 118, 119, 121, 123, 125
EXAMPLE
R(1) = 1; trace = 1, positive.
R(2) = 4 - 2; trace = -2, negative.
R(3) = 4 - 1; trace = -1, negative.
MATHEMATICA
b[n_] := n^2; bb = Table[b[n], {n, 0, 1000}];
s[n_] := Table[b[n], {k, 1, 2 n - 1}];
h[1] = {1}; h[n_] := Join[h[n - 1], s[n]];
g = h[100]; r[0] = {0}; r[1] = {1}; r[2] = {4, -2};
r[n_] := If[MemberQ[bb, n], {n}, Join[{g[[n]]}, -r[g[[n]] - n]]];
Table[r[n], {n, 0, 120}] (* A256789 *) u = Flatten[Table[Last[r[n]], {n, 1, 1000}]]; (* A256791 *) Select[Range[800], u[[#]] > 0 &] (* A256792 *) Select[Range[800], u[[#]] < 0 &] (* A256793 *)
Numbers whose minimal alternating squares representation has positive trace.
+10
4
2, 3, 5, 8, 10, 12, 15, 18, 19, 21, 24, 27, 29, 30, 32, 35, 38, 40, 42, 43, 45, 48, 50, 51, 53, 55, 57, 58, 60, 63, 65, 67, 68, 70, 72, 74, 75, 77, 80, 83, 84, 86, 87, 89, 91, 93, 94, 96, 99, 101, 104, 105, 107, 108, 110, 112, 114, 115, 117, 120, 122, 124
EXAMPLE
R(1) = 1; trace = 1, positive.
R(2) = 4 - 2; trace = -2, negative.
R(3) = 4 - 1; trace = -1, negative.
MATHEMATICA
b[n_] := n^2; bb = Table[b[n], {n, 0, 1000}];
s[n_] := Table[b[n], {k, 1, 2 n - 1}];
h[1] = {1}; h[n_] := Join[h[n - 1], s[n]];
g = h[100]; r[0] = {0}; r[1] = {1}; r[2] = {4, -2};
r[n_] := If[MemberQ[bb, n], {n}, Join[{g[[n]]}, -r[g[[n]] - n]]];
Table[r[n], {n, 0, 120}] (* A256789 *) u = Flatten[Table[Last[r[n]], {n, 1, 1000}]]; (* A256791 *) Select[Range[800], u[[#]] > 0 &] (* A256792 *) Select[Range[800], u[[#]] < 0 &] (* A256793 *)
3, 2, 1, 2, 2, 2, 1, 2, 1, 3, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 2, 3, 2, 1, 2, 3, 2, 2, 3, 2, 1, 2, 2, 3, 2, 2, 3, 2, 1, 2, 1, 3, 3, 2, 2, 3, 2, 1, 2, 2, 1, 3, 3, 2, 2, 3, 2, 1, 2, 2, 2, 1, 3, 3, 2, 2, 3, 2, 1, 2, 1, 3, 2, 1, 3, 3, 2, 2, 3, 2, 1, 2, 3, 3, 2
EXAMPLE
R(0) = 0;
R(1) = 1;
R(2) = 4 - 2;
R(3) = 4 - 1;
R(4) = 4;
R(5) = 9 - 4.
MATHEMATICA
b[n_] := n^2; bb = Table[b[n], {n, 0, 1000}]; (* Squares as base *)
s[n_] := Table[b[n], {k, 1, 2 n - 1}];
h[1] = {1}; h[n_] := Join[h[n - 1], s[n]];
g = h[100]; r[0] = {0}; r[1] = {1}; r[2] = {4, -2};
r[n_] := If[MemberQ[bb, n], {n}, Join[{g[[n]]}, -r[g[[n]] - n]]];
Table[r[n], {n, 0, 120}]; (* A256789 *) u = Flatten[Table[Last[r[n]], {n, 1, 1000}]]; (* A256791 *) u1 = Select[Range[800], u[[#]] > 0 &]; (* A256792 *) u2 = Select[Range[800], u[[#]] < 0 &]; (* A256793 *)
1, 2, 3, 2, 2, 3, 3, 1, 2, 3, 3, 2, 1, 2, 3, 3, 2, 2, 1, 2, 3, 2, 1, 2, 2, 2, 1, 2, 3, 2, 2, 1, 2, 2, 2, 1, 2, 3, 3, 1, 2, 1, 2, 2, 2, 1, 2, 3, 2, 3, 1, 2, 1, 2, 2, 2, 1, 2, 3, 2, 2, 3, 1, 2, 1, 2, 2, 2, 1, 2, 3, 3, 1, 2, 3, 1, 2, 1, 2, 2, 2, 1, 2, 3, 2, 1
COMMENTS
These are the numbers of consecutive positive traces when the minimal alternating squares representations for positive integers are written in order. Is every term < 5? The first term greater than 3 is a(116) = 4, corresponding to these 3 consecutive representations:
R(225) = 225;
R(226) = 256 - 36 + 9 - 4 + 1;
R(227) = 256 - 36 + 9 - 4 + 2.
MATHEMATICA
b[n_] := n^2; bb = Table[b[n], {n, 0, 1000}]; (* Squares as base *)
s[n_] := Table[b[n], {k, 1, 2 n - 1}];
h[1] = {1}; h[n_] := Join[h[n - 1], s[n]];
g = h[100]; r[0] = {0}; r[1] = {1}; r[2] = {4, -2};
r[n_] := If[MemberQ[bb, n], {n}, Join[{g[[n]]}, -r[g[[n]] - n]]];
Table[r[n], {n, 0, 120}]; (* A256789 *) u = Flatten[Table[Last[r[n]], {n, 1, 1000}]]; (* A256791 *) u1 = Select[Range[800], u[[#]] > 0 &]; (* A256792 *) u2 = Select[Range[800], u[[#]] < 0 &]; (* A256793 *)
Positive part of the minimal alternating squares representation of n.
+10
2
1, 4, 4, 4, 9, 10, 11, 9, 9, 20, 20, 16, 17, 18, 16, 16, 26, 29, 29, 29, 25, 26, 27, 25, 25, 46, 36, 37, 40, 40, 40, 36, 37, 38, 36, 36, 53, 58, 59, 49, 50, 53, 53, 53, 49, 50, 51, 49, 49, 68, 68, 68, 73, 74, 64, 65, 68, 68, 68, 64, 65, 66, 64, 64, 81, 82
EXAMPLE
R(1) = 1, positive part 1, nonpositive part 0;
R(2) = 4 - 2, positive part 4, nonpositive part 2;
R(3) = 4 - 1, positive part 4, nonpositive part 1;
R(89) = 100 - 16 + 9 - 4, positive part 100 + 9 = 109, nonpositive part 16 + 4 = 20.
MATHEMATICA
b[n_] := n^2; bb = Table[b[n], {n, 0, 100}];
s[n_] := Table[b[n], {k, 1, 2 n - 1}];
h[1] = {1}; h[n_] := Join[h[n - 1], s[n]];
g = h[100]; r[0] = {0}; r[1] = {1}; r[2] = {4, -2};
r[n_] := If[MemberQ[bb, n], {n}, Join[{g[[n]]}, -r[g[[n]] - n]]];
t = Table[r[n], {n, 1, z}] (* A256789 *) Table[Total[(Abs[r[n]] + r[n])/2], {n, 1, 120}] (* A256796 *) Table[Total[(Abs[r[n]] - r[n])/2], {n, 1, 120}] (* A256797 *)
Nonpositive part of the minimal alternating squares representation of n.
+10
2
0, 2, 1, 0, 4, 4, 4, 1, 0, 10, 9, 4, 4, 4, 1, 0, 9, 11, 10, 9, 4, 4, 4, 1, 0, 20, 9, 9, 11, 10, 9, 4, 4, 4, 1, 0, 16, 20, 20, 9, 9, 11, 10, 9, 4, 4, 4, 1, 0, 18, 17, 16, 20, 20, 9, 9, 11, 10, 9, 4, 4, 4, 1, 0, 16, 16, 18, 17, 16, 20, 20, 9, 9, 11, 10, 9, 4
EXAMPLE
R(1) = 1, positive part 1, nonpositive part 0;
R(2) = 4 - 2, positive part 4, nonpositive part 2;
R(3) = 4 - 1, positive part 4, nonpositive part 1;
R(89) = 100 - 16 + 9 - 4, positive part 100 + 9 = 109, nonpositive part 16 + 4 = 20.
MATHEMATICA
b[n_] := n^2; bb = Table[b[n], {n, 0, 100}];
s[n_] := Table[b[n], {k, 1, 2 n - 1}];
h[1] = {1}; h[n_] := Join[h[n - 1], s[n]];
g = h[100]; r[0] = {0}; r[1] = {1}; r[2] = {4, -2};
r[n_] := If[MemberQ[bb, n], {n}, Join[{g[[n]]}, -r[g[[n]] - n]]];
t = Table[r[n], {n, 1, z}] (* A256789 *) Table[Total[(Abs[r[n]] + r[n])/2], {n, 1, 120}] (* A256796 *) Table[Total[(Abs[r[n]] - r[n])/2], {n, 1, 120}] (* A256797 *)
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