Displaying 1-10 of 24 results found.
Expansion of Product_{k>=1} (1 + 2^(k-1)*x^k).
+10
37
1, 1, 2, 6, 12, 32, 72, 176, 384, 960, 2112, 4992, 11264, 26112, 58368, 136192, 301056, 688128, 1548288, 3489792, 7766016, 17596416, 38993920, 87293952, 194248704, 432537600, 957349888, 2132803584, 4699717632, 10406068224, 23001563136, 50683969536, 111434268672, 245819768832
COMMENTS
Number of compositions of partitions of n into distinct parts. a(3) = 6: 3, 21, 12, 111, 2|1, 11|1. - Alois P. Heinz, Sep 16 2019 Also the number of ways to split a composition of n into contiguous subsequences with strictly decreasing sums. - Gus Wiseman, Jul 13 2020 This sequence is obtained from the generalized Euler transform in A266964 by taking f(n) = -1, g(n) = (-1) * 2^(n-1). - Seiichi Manyama, Aug 22 2020
FORMULA
G.f.: Product_{k>=1} (1 + A011782(k)*x^k). a(n) ~ 2^n * exp(2*sqrt(-polylog(2, -1/2)*n)) * (-polylog(2, -1/2))^(1/4) / (sqrt(6*Pi) * n^(3/4)). - Vaclav Kotesovec, Sep 19 2019
EXAMPLE
The a(0) = 1 through a(4) = 12 splittings:
() (1) (2) (3) (4)
(1,1) (1,2) (1,3)
(2,1) (2,2)
(1,1,1) (3,1)
(2),(1) (1,1,2)
(1,1),(1) (1,2,1)
(2,1,1)
(3),(1)
(1,1,1,1)
(1,2),(1)
(2,1),(1)
(1,1,1),(1)
(End)
MATHEMATICA
nmax = 33; CoefficientList[Series[Product[(1 + 2^(k - 1) x^k), {k, 1, nmax}], {x, 0, nmax}], x]
PROG
(PARI) N=40; x='x+O('x^N); Vec(prod(k=1, N, 1+2^(k-1)*x^k)) \\ Seiichi Manyama, Aug 22 2020
CROSSREFS
Starting with a reversed partition gives A323583. Starting with a partition gives A336134. Partitions of partitions are A001970. Splittings with equal sums are A074854. Splittings of compositions are A133494. Splittings with distinct sums are A336127.
First differences of the binomial transform of the partition numbers ( A000041).
+10
30
1, 1, 3, 8, 21, 54, 137, 344, 856, 2113, 5179, 12614, 30548, 73595, 176455, 421215, 1001388, 2371678, 5597245, 13166069, 30873728, 72185937, 168313391, 391428622, 908058205, 2101629502, 4853215947, 11183551059, 25718677187, 59030344851, 135237134812, 309274516740
COMMENTS
a(n) = A103446(n) for n>=1; here a(0) is set to 1 in accordance with the definition and other important generating functions. Also the number of sequences of compositions ( A133494) with weakly decreasing lengths and total sum n. For example, the a(0) = 1 through a(3) = 8 sequences are: () ((1)) ((2)) ((3))
((11)) ((12))
((1)(1)) ((21))
((111))
((1)(2))
((2)(1))
((11)(1))
((1)(1)(1))
The case of constant lengths is A101509. The case of strictly decreasing lengths is A129519. The case of sequences of partitions is A141199. The case of twice-partitions is A358831. (End)
FORMULA
G.f.: Product_{n>=1} (1-x)^n / ((1-x)^n - x^n).
G.f.: Sum_{n>=0} x^n * (1-x)^(n*(n-1)/2) / Product_{k=1..n} ((1-x)^k - x^k).
G.f.: Sum_{n>=0} x^(n^2) * (1-x)^n / Product_{k=1..n} ((1-x)^k - x^k)^2.
G.f.: exp( Sum_{n>=1} x^n/((1-x)^n - x^n) / n ).
G.f.: exp( Sum_{n>=1} sigma(n) * x^n/(1-x)^n / n ), where sigma(n) is the sum of divisors of n ( A000203). G.f.: Product_{n>=1} (1 + x^n/(1-x)^n)^ A001511(n), where 2^ A001511(n) is the highest power of 2 that divides 2*n. a(n) ~ exp(Pi*sqrt(n/3) + Pi^2/24) * 2^(n-2) / (n*sqrt(3)). - Vaclav Kotesovec, Jun 25 2015
EXAMPLE
G.f.: A(x) = 1 + x + 3*x^2 + 8*x^3 + 21*x^4 + 54*x^5 + 137*x^6 + 344*x^7 +...
The g.f. equals the product:
A(x) = (1-x)/((1-x)-x) * (1-x)^2/((1-x)^2-x^2) * (1-x)^3/((1-x)^3-x^3) * (1-x)^4/((1-x)^4-x^4) * (1-x)^5/((1-x)^5-x^5) * (1-x)^6/((1-x)^6-x^6) * (1-x)^7/((1-x)^7-x^7) *...
and also equals the series:
A(x) = 1 + x*(1-x)/((1-x)-x)^2 + x^4*(1-x)^2/(((1-x)-x)*((1-x)^2-x^2))^2 + x^9*(1-x)^3/(((1-x)-x)*((1-x)^2-x^2)*((1-x)^3-x^3))^2 + x^16*(1-x)^4/(((1-x)-x)*((1-x)^2-x^2)*((1-x)^3-x^3)*((1-x)^4-x^4))^2 +...
MAPLE
b:= proc(n) option remember;
add(combinat[numbpart](k)*binomial(n, k), k=0..n)
end:
a:= n-> b(n)-b(n-1):
MATHEMATICA
Flatten[{1, Table[Sum[Binomial[n-1, k]*PartitionsP[k+1], {k, 0, n-1}], {n, 1, 30}]}] (* Vaclav Kotesovec, Jun 25 2015 *)
PROG
(PARI) {a(n)=sum(k=0, n, (binomial(n, k)-if(n>0, binomial(n-1, k)))*numbpart(k))}
for(n=0, 40, print1(a(n), ", "))
(PARI) {a(n)=local(X=x+x*O(x^n)); polcoeff(prod(k=1, n, (1-x)^k/((1-x)^k-X^k)), n)}
(PARI) {a(n)=local(X=x+x*O(x^n)); polcoeff(sum(m=0, n, x^m*(1-x)^(m*(m-1)/2)/prod(k=1, m, ((1-x)^k - X^k))), n)}
(PARI) {a(n)=local(X=x+x*O(x^n)); polcoeff(sum(m=0, n, x^(m^2)*(1-X)^m/prod(k=1, m, ((1-x)^k - x^k)^2)), n)}
(PARI) {a(n)=local(X=x+x*O(x^n)); polcoeff(exp(sum(m=1, n+1, x^m/((1-x)^m-X^m)/m)), n)}
(PARI) {a(n)=local(X=x+x*O(x^n)); polcoeff(exp(sum(m=1, n+1, sigma(m)*x^m/(1-X)^m/m)), n)}
(PARI) {a(n)=local(X=x+x*O(x^n)); polcoeff(prod(k=1, n, (1 + x^k/(1-X)^k)^valuation(2*k, 2)), n)}
CROSSREFS
Cf. A000041, A000219, A011782, A055887, A063834, A075900, A098407, A101509, A103446, A129519, A141199, A218481.
Number of finite sequences of distinct integer partitions with total sum n.
+10
9
1, 1, 2, 7, 13, 35, 87, 191, 470, 1080, 2532, 5778, 13569, 30715, 69583, 160386, 360709, 814597, 1824055, 4102430, 9158405, 20378692, 45215496, 100055269, 221388993, 486872610, 1069846372, 2343798452, 5127889666, 11186214519, 24351106180, 52896439646
EXAMPLE
The a(1) = 1 through a(4) = 13 sequences:
((1)) ((2)) ((3)) ((4))
((11)) ((21)) ((22))
((111)) ((31))
((1)(2)) ((211))
((2)(1)) ((1111))
((1)(11)) ((1)(3))
((11)(1)) ((3)(1))
((11)(2))
((1)(21))
((2)(11))
((21)(1))
((1)(111))
((111)(1))
MAPLE
b:= proc(n, i, p) option remember; `if`(n=0, p!, `if`(i<1, 0, add(
binomial(combinat[numbpart](i), j)*b(n-i*j, i-1, p+j), j=0..n/i)))
end:
a:= n-> b(n$2, 0):
MATHEMATICA
ptnseq[n_]:=Join@@Table[Tuples[IntegerPartitions/@comp], {comp, Join@@Permutations/@IntegerPartitions[n]}];
Table[Length[Select[ptnseq[n], UnsameQ@@#&]], {n, 0, 10}]
CROSSREFS
This is the case of A055887 with distinct partitions. The case of twice-partitions is A296122. The version for sequences of compositions is A358907. The case of weakly decreasing lengths is A358908. The case of distinct lengths is A358912. The version for strict partitions is A358913, distinct case of A304969. A001970 counts multiset partitions of integer partitions.
A358830 counts twice-partitions with distinct lengths.
A358901 counts partitions with all distinct Omegas.
Expansion of Product_{k>=1} (1 + x^k)^(6^(k-1)).
+10
8
1, 1, 6, 42, 267, 1743, 11234, 72470, 466251, 2996883, 19234836, 123315828, 789682546, 5051601010, 32282443044, 206104519572, 1314652656453, 8378283675645, 53350205335626, 339445117302366, 2158091256282273, 13710402587540469, 87040883294333382, 552205562345916570
FORMULA
a(n) ~ exp(sqrt(2*n/3) - 1/12 - c/6) * 6^(n - 1/4) / (2*sqrt(Pi)*n^(3/4)), where c = Sum_{j>=2} (-1)^j / (j * (6^(j-1) - 1)). - Vaclav Kotesovec, Apr 13 2021
MAPLE
N:= 100: # for a(0)..a(N)
G:= mul((1+x^k)^(6^(k-1)), k=1..N):
S:= series(G, x, N+1):
MATHEMATICA
nmax = 23; CoefficientList[Series[Product[(1 + x^k)^(6^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[(-1)^(k/d + 1) d 6^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 23}]
PROG
(PARI) seq(n)={Vec(prod(k=1, n, (1 + x^k + O(x*x^n))^(6^(k-1))))} \\ Andrew Howroyd, Apr 12 2021
Number of finite sequences of distinct integer compositions with total sum n.
+10
8
1, 1, 2, 8, 18, 54, 156, 412, 1168, 3200, 8848, 24192, 66632, 181912, 495536, 1354880, 3680352, 9997056, 27093216, 73376512, 198355840, 535319168, 1443042688, 3884515008, 10445579840, 28046885824, 75225974912, 201536064896, 539339293824, 1441781213952
EXAMPLE
The a(1) = 1 through a(4) = 18 sequences:
((1)) ((2)) ((3)) ((4))
((11)) ((12)) ((13))
((21)) ((22))
((111)) ((31))
((1)(2)) ((112))
((2)(1)) ((121))
((1)(11)) ((211))
((11)(1)) ((1111))
((1)(3))
((3)(1))
((1)(12))
((11)(2))
((1)(21))
((12)(1))
((2)(11))
((21)(1))
((1)(111))
((111)(1))
MAPLE
g:= proc(n) option remember; ceil(2^(n-1)) end:
b:= proc(n, i, p) option remember; `if`(n=0, p!, `if`(i<1, 0, (t->
add(binomial(t, j)*b(n-i*j, i-1, p+j), j=0..min(t, n/i)))(g(i))))
end:
a:= n-> b(n$2, 0):
MATHEMATICA
comps[n_]:=Join@@Permutations/@IntegerPartitions[n];
Table[Length[Select[Join@@Table[Tuples[comps/@c], {c, comps[n]}], UnsameQ@@#&]], {n, 0, 10}]
CROSSREFS
This is the strict case of A133494. The version for sequences of partitions is A358906. A001970 counts multiset partitions of integer partitions.
A218482 counts sequences of compositions with weakly decreasing lengths.
A358830 counts twice-partitions with distinct lengths.
A358901 counts partitions with all different Omegas.
A358914 counts twice-partitions into distinct strict partitions.
Cf. A000009, A000041, A000219, A055887, A075900, A296122, A304961, A307068, A336342, A358836, A358912.
Expansion of Product_{k>=1} (1 + x^k)^(3^(k-1)).
+10
7
1, 1, 3, 12, 39, 138, 469, 1603, 5427, 18372, 61869, 207909, 696537, 2328039, 7762266, 25826142, 85749969, 284171598, 940027872, 3104280885, 10234808334, 33692547249, 110753171784, 363561071175, 1191860487561, 3902350627434, 12761565487173, 41685086306917, 136012008938158
FORMULA
a(n) ~ exp(2*sqrt(n/3) - 1/6 - c/3) * 3^(n - 1/4) / (2*sqrt(Pi)*n^(3/4)), where c = Sum_{j>=2} (-1)^j / (j * (3^(j-1) - 1)). - Vaclav Kotesovec, Apr 13 2021
MAPLE
h:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
add(h(n-i*j, i-1)*binomial(3^(i-1), j), j=0..n/i)))
end:
a:= n-> h(n$2):
MATHEMATICA
nmax = 28; CoefficientList[Series[Product[(1 + x^k)^(3^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[(-1)^(k/d + 1) d 3^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 28}]
PROG
(PARI) seq(n)={Vec(prod(k=1, n, (1 + x^k + O(x*x^n))^(3^(k-1))))} \\ Andrew Howroyd, Apr 12 2021
Expansion of Product_{k>=1} (1 + x^k)^(4^(k-1)).
+10
7
1, 1, 4, 20, 86, 390, 1724, 7644, 33697, 148401, 651584, 2855840, 12491276, 54540636, 237733768, 1034610232, 4495832776, 19508749928, 84540638312, 365888222552, 1581630245756, 6829047398156, 29453496620000, 126898489491904, 546183557447366, 2348560270762006, 10089340886428928
FORMULA
a(n) ~ exp(sqrt(n) - 1/8 - c/4) * 2^(2*n - 3/2) / (sqrt(Pi)*n^(3/4)), where c = Sum_{j>=2} (-1)^j / (j * (4^(j-1) - 1)). - Vaclav Kotesovec, Apr 13 2021
MAPLE
h:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
add(h(n-i*j, i-1)*binomial(4^(i-1), j), j=0..n/i)))
end:
a:= n-> h(n$2):
MATHEMATICA
nmax = 26; CoefficientList[Series[Product[(1 + x^k)^(4^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[(-1)^(k/d + 1) d 4^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 26}]
PROG
(PARI) seq(n)={Vec(prod(k=1, n, (1 + x^k + O(x*x^n))^(4^(k-1))))} \\ Andrew Howroyd, Apr 12 2021
Expansion of Product_{k>=1} (1 + x^k)^(5^(k-1)).
+10
7
1, 1, 5, 30, 160, 885, 4810, 26185, 142005, 769305, 4159301, 22455876, 121057525, 651737675, 3504241650, 18818709130, 100945053055, 540885242825, 2895159035375, 15481318817450, 82704855762375, 441427664993275, 2354020475714775, 12542918682786300, 66778882780674975
FORMULA
a(n) ~ exp(2*sqrt(n/5) - 1/10 - c/5) * 5^(n - 1/4) / (2*sqrt(Pi)*n^(3/4)), where c = Sum_{j>=2} (-1)^j / (j * (5^(j-1) - 1)). - Vaclav Kotesovec, Apr 13 2021
MAPLE
h:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
add(h(n-i*j, i-1)*binomial(5^(i-1), j), j=0..n/i)))
end:
a:= n-> h(n$2):
MATHEMATICA
nmax = 24; CoefficientList[Series[Product[(1 + x^k)^(5^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[(-1)^(k/d + 1) d 5^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 24}]
PROG
(PARI) seq(n)={Vec(prod(k=1, n, (1 + x^k + O(x*x^n))^(5^(k-1))))} \\ Andrew Howroyd, Apr 12 2021
Expansion of Product_{k>=1} (1 + x^k)^(7^(k-1)).
+10
7
1, 1, 7, 56, 413, 3108, 23163, 172711, 1285256, 9556603, 70980000, 526711507, 3904946864, 28926003505, 214095348671, 1583389916081, 11701578676851, 86415267247743, 637732279701496, 4703270177738076, 34664585073280204, 255332979654402524, 1879629724498860397, 13829015594546304600
FORMULA
a(n) ~ exp(2*sqrt(n/7) - 1/14 - c/7) * 7^(n - 1/4) / (2*sqrt(Pi)*n^(3/4)), where c = Sum_{j>=2} (-1)^j / (j * (7^(j-1) - 1)). - Vaclav Kotesovec, Apr 13 2021
MAPLE
h:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
add(h(n-i*j, i-1)*binomial(7^(i-1), j), j=0..n/i)))
end:
a:= n-> h(n$2):
MATHEMATICA
nmax = 23; CoefficientList[Series[Product[(1 + x^k)^(7^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[(-1)^(k/d + 1) d 7^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 23}]
PROG
(PARI) seq(n)={Vec(prod(k=1, n, (1 + x^k + O(x*x^n))^(7^(k-1))))} \\ Andrew Howroyd, Apr 12 2021
Expansion of Product_{k>=1} (1 + x^k)^(8^(k-1)).
+10
7
1, 1, 8, 72, 604, 5148, 43544, 368408, 3112262, 26273542, 221605240, 1867736120, 15730022540, 132385106956, 1113413229000, 9358220560136, 78606905495809, 659886123312449, 5536404584185376, 46424396382193376, 389074608184431328, 3259085506224931424, 27286163457927575200
FORMULA
a(n) ~ exp(sqrt(n/2) - 1/16 - c/8) * 2^(3*n - 7/4) / (sqrt(Pi)*n^(3/4)), where c = Sum_{j>=2} (-1)^j / (j * (8^(j-1) - 1)). - Vaclav Kotesovec, Apr 13 2021
MAPLE
h:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
add(h(n-i*j, i-1)*binomial(8^(i-1), j), j=0..n/i)))
end:
a:= n-> h(n$2):
MATHEMATICA
nmax = 22; CoefficientList[Series[Product[(1 + x^k)^(8^(k - 1)), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, (1/n) Sum[Sum[(-1)^(k/d + 1) d 8^(d - 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]]; Table[a[n], {n, 0, 22}]
PROG
(PARI) seq(n)={Vec(prod(k=1, n, (1 + x^k + O(x*x^n))^(8^(k-1))))} \\ Andrew Howroyd, Apr 12 2021
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