A027346 -id:A027346 - cp's OEIS frontend

A026007 Expansion of Product_{m>=1} (1 + q^m)^m; number of partitions of n into distinct parts, where n different parts of size n are available.

1, 1, 2, 5, 8, 16, 28, 49, 83, 142, 235, 385, 627, 1004, 1599, 2521, 3940, 6111, 9421, 14409, 21916, 33134, 49808, 74484, 110837, 164132, 241960, 355169, 519158, 755894, 1096411, 1584519, 2281926, 3275276, 4685731, 6682699, 9501979, 13471239, 19044780, 26850921, 37756561, 52955699

Offset: 0

N. J. A. Sloane

In general, for t > 0, if g.f. = Product_{m>=1} (1 + t*q^m)^m then a(n) ~ c^(1/6) * exp(3^(2/3) * c^(1/3) * n^(2/3) / 2) / (3^(2/3) * (t+1)^(1/12) * sqrt(2*Pi) * n^(2/3)), where c = Pi^2*log(t) + log(t)^3 - 6*polylog(3, -1/t). - Vaclav Kotesovec, Jan 04 2016

			For n = 4, we have 8 partitions
  01: [4]
  02: [4']
  03: [4'']
  04: [4''']
  05: [3, 1]
  06: [3', 1]
  07: [3'', 1]
  08: [2, 2']

Alois P. Heinz, Table of n, a(n) for n = 0..10000
Lida Ahmadi, Ricardo Gómez Aíza, and Mark Daniel Ward, A unified treatment of families of partition functions, La Matematica (2024). Preprint available as arXiv:2303.02240 [math.CO], 2023.
Vaclav Kotesovec, Graph - The asymptotic ratio
Vaclav Kotesovec, A method of finding the asymptotics of q-series based on the convolution of generating functions, arXiv:1509.08708 [math.CO], Sep 30 2015, p. 18.

Cf. A000009, A000027, A026741, A073592, A255528, A261562, A266857, A285223, A304040.
Cf. A000219. - Gary W. Adamson, Jun 13 2009
Cf. A027998, A248882, A248883, A248884.
Cf. A026011, A027346, A027906.
Column k=1 of A284992.

with(numtheory):
b:= proc(n) option remember;
      add((-1)^(n/d+1)*d^2, d=divisors(n))
    end:
a:= proc(n) option remember;
      `if`(n=0, 1, add(b(k)*a(n-k), k=1..n)/n)
    end:
seq(a(n), n=0..45);  # Alois P. Heinz, Aug 03 2013

a[n_] := a[n] = 1/n*Sum[Sum[(-1)^(k/d+1)*d^2, {d, Divisors[k]}]*a[n-k], {k, 1, n}]; a[0] = 1; Table[a[n], {n, 0, 41}] (* Jean-François Alcover, Apr 17 2014, after Vladeta Jovovic *)
nmax=50; CoefficientList[Series[Exp[Sum[(-1)^(k+1)*x^k/(k*(1-x^k)^2),{k,1,nmax}]],{x,0,nmax}],x] (* Vaclav Kotesovec, Feb 28 2015 *)

N=66; q='q+O('q^N);
gf= prod(n=1,N, (1+q^n)^n );
Vec(gf)
/* Joerg Arndt, Oct 06 2012 */

a(n) = (1/n)*Sum_{k=1..n} A078306(k)*a(n-k). - Vladeta Jovovic, Nov 22 2002
G.f.: Product_{m>=1} (1+x^m)^m. Weighout transform of natural numbers (A000027). Euler transform of A026741. - Franklin T. Adams-Watters, Mar 16 2006
a(n) ~ zeta(3)^(1/6) * exp((3/2)^(4/3) * zeta(3)^(1/3) * n^(2/3)) / (2^(3/4) * 3^(1/3) * sqrt(Pi) * n^(2/3)), where zeta(3) = A002117. - Vaclav Kotesovec, Mar 05 2015

A026011 Expansion of Product_{m>=1} (1 + q^m)^(2*m).

Original entry on oeis.org

1, 2, 5, 14, 30, 68, 145, 298, 600, 1182, 2280, 4318, 8064, 14824, 26917, 48292, 85675, 150466, 261762, 451328, 771739, 1309362, 2205109, 3687904, 6127155, 10116074, 16602508, 27093582, 43974355, 71003224

Offset: 0

N. J. A. Sloane

nonn

Seiichi Manyama, Table of n, a(n) for n = 0..10000 (terms 0..1000 from G. C. Greubel)
Vaclav Kotesovec, A method of finding the asymptotics of q-series based on the convolution of generating functions, arXiv:1509.08708 [math.CO], Sep 30 2015, p. 19.

Column k=2 of A277938.

Cf. A026007, A027346, A027906.

nmax = 40; CoefficientList[Series[Product[(1+x^k)^(2*k), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Aug 17 2015 *)

a(n) ~ Zeta(3)^(1/6) * exp(3^(4/3) * Zeta(3)^(1/3) * n^(2/3)/2) / (2^(2/3) * 3^(1/3) * sqrt(Pi) * n^(2/3)). - Vaclav Kotesovec, Aug 17 2015

G.f.: exp(2*Sum_{k>=1} (-1)^(k+1)*x^k/(k*(1 - x^k)^2)). - Ilya Gutkovskiy, May 30 2018

A262878 Expansion of Product_{k>=1} (1+x^(3*k-1))^k.

Original entry on oeis.org

1, 0, 1, 0, 0, 2, 0, 2, 3, 0, 4, 4, 1, 10, 5, 6, 16, 6, 14, 28, 10, 32, 40, 18, 63, 60, 42, 112, 83, 84, 187, 124, 172, 300, 186, 320, 456, 302, 581, 684, 507, 982, 1004, 874, 1624, 1476, 1508, 2566, 2174, 2582, 3981, 3262, 4338, 6002, 4945, 7138, 8947, 7660

Offset: 0

Vaclav Kotesovec, Oct 04 2015

nonn

In general, if s>0, t>0, GCD(s,t)=1 and g.f. = Product_{k>=1} (1 + x^(s*k-t))^k then a(n) ~ 2^(t^2/(2*s^2) - 3/4) * s^(2/3) * Zeta(3)^(1/6) * exp(-Pi^4 * t^2 / (1296 * s^2 * Zeta(3)) + Pi^2 * t * 2^(1/3) * 3^(2/3) * s^(2/3) * n^(1/3) / (36 * s^2 * Zeta(3)^(1/3)) + 3^(4/3) * Zeta(3)^(1/3) * n^(2/3) / (2^(4/3) * s^(2/3)) ) / (3^(1/3) * s * sqrt(Pi) * n^(2/3)). - Vaclav Kotesovec, Oct 12 2015

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000
Vaclav Kotesovec, A method of finding the asymptotics of q-series based on the convolution of generating functions, arXiv:1509.08708 [math.CO], Sep 30 2015

Cf. A026007, A027346, A035528, A262876, A262877, A262879, A262884, A262948, A263138, A263145.

with(numtheory):
b:= n-> `if`(n<3, n-1, (p-> [0, -r, 2*r, 0, 0, 2*r+1][p]
         )(1+irem(n+3, 6, 'r'))):
a:= proc(n) option remember; `if`(n=0, 1, add(add(
      d*b(d), d=divisors(j))*a(n-j), j=1..n)/n)
    end:
seq(a(n), n=0..60);  # Alois P. Heinz, Oct 05 2015

nmax=100; CoefficientList[Series[Product[(1+x^(3k-1))^k, {k, 1, nmax}], {x, 0, nmax}], x]
nmax=100; CoefficientList[Series[E^Sum[(-1)^(j+1)/j*x^(2*j)/(1-x^(3j))^2,{j,1,nmax}],{x,0,nmax}],x]

a(n) ~ exp(2^(-4/3) * 3^(2/3) * Zeta(3)^(1/3) * n^(2/3) + Pi^2 * n^(1/3) / (2^(5/3)*3^(8/3) * Zeta(3)^(1/3)) - Pi^4/(11664*Zeta(3))) * Zeta(3)^(1/6) / (2^(25/36) * 3^(2/3) * sqrt(Pi) * n^(2/3)).

A262879 Expansion of Product_{k>=1} (1+x^(3*k-2))^k.

Original entry on oeis.org

1, 1, 0, 0, 2, 2, 0, 3, 4, 1, 4, 10, 6, 5, 16, 14, 9, 28, 32, 17, 40, 63, 41, 63, 112, 83, 94, 187, 171, 156, 301, 319, 260, 467, 580, 465, 713, 981, 818, 1095, 1627, 1452, 1682, 2584, 2510, 2632, 4047, 4266, 4162, 6181, 7054, 6685, 9396, 11423, 10753, 14132

Offset: 0

Vaclav Kotesovec, Oct 04 2015

nonn

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000
Vaclav Kotesovec, A method of finding the asymptotics of q-series based on the convolution of generating functions, arXiv:1509.08708 [math.CO], Sep 30 2015

Cf. A026007, A027346, A035528, A262876, A262877, A262878, A262884, A262949.

nmax=100; CoefficientList[Series[Product[(1+x^(3k-2))^k, {k, 1, nmax}], {x, 0, nmax}], x]
nmax=100; CoefficientList[Series[E^Sum[(-1)^(j+1)/j*x^j/(1-x^(3j))^2,{j,1,nmax}],{x,0,nmax}],x]
Clear[a]; a[n_]:=a[n] = If[n==0, 1, Sum[Sum[d*{0, 2*Floor[d/6] + 1, -Floor[d/6] - 1, 0, 2*Floor[d/6] + 2, 0}[[1 + Mod[d, 6]]], {d, Divisors[j]}] * a[n-j], {j, 1, n}]/n]; Table[a[n], {n, 0, 100}]

a(n) ~ exp(2^(-4/3) * 3^(2/3) * Zeta(3)^(1/3) * n^(2/3) + Pi^2 * n^(1/3) / (2^(2/3) * 3^(8/3) * Zeta(3)^(1/3)) - Pi^4/(2916*Zeta(3))) * Zeta(3)^(1/6) / (2^(19/36) * 3^(2/3) * sqrt(Pi) * n^(2/3)).

A341385 Expansion of (-1 + Product_{k>=1} (1 + x^k)^k)^3.

Original entry on oeis.org

1, 6, 27, 92, 279, 762, 1952, 4725, 10968, 24551, 53346, 112932, 233755, 474288, 945384, 1854517, 3585534, 6841182, 12895246, 24035841, 44337672, 80999765, 146644746, 263249169, 468817933, 828658233, 1454315508, 2535217624, 4391290854, 7560034419, 12939963016

Offset: 3

Ilya Gutkovskiy, Feb 10 2021

nonn

Alois P. Heinz, Table of n, a(n) for n = 3..10000

Cf. A026007, A027346, A321948, A327381, A341384, A341386, A341387, A341388, A341390, A341391.

g:= proc(n) option remember; `if`(n=0, 1, add(g(n-j)*add(d^2/
     `if`(d::odd, 1, 2), d=numtheory[divisors](j)), j=1..n)/n)
    end:
b:= proc(n, k) option remember; `if`(k=0, 1, `if`(k=1, `if`(n=0, 0,
      g(n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2))))
    end:
a:= n-> b(n, 3):
seq(a(n), n=3..33);  # Alois P. Heinz, Feb 10 2021

nmax = 33; CoefficientList[Series[(-1 + Product[(1 + x^k)^k, {k, 1, nmax}])^3, {x, 0, nmax}], x] // Drop[#, 3] &

a(n) ~ A027346(n). - Vaclav Kotesovec, Feb 20 2021

A027906 Expansion of Product_{m>=1} (1+q^m)^(4*m).

Original entry on oeis.org

1, 4, 14, 48, 141, 396, 1058, 2696, 6646, 15884, 36956, 83976, 186849, 407864, 875030, 1847824, 3845520, 7895872, 16010610, 32088120, 63611656, 124817444, 242560418, 467095640, 891754784, 1688619460

Offset: 0

N. J. A. Sloane

nonn

In general, if g.f. = Product_{m>=1} (1+x^m)^(t*m) and t>=1, then a(n) ~ 2^(-2/3 - t/12) * exp((3/2)^(4/3) * t^(1/3) * Zeta(3)^(1/3) * n^(2/3)) * t^(1/6) * Zeta(3)^(1/6) / (3^(1/3) * sqrt(Pi) * n^(2/3)). - Vaclav Kotesovec, Aug 17 2015

Seiichi Manyama, Table of n, a(n) for n = 0..10000
Vaclav Kotesovec, A method of finding the asymptotics of q-series based on the convolution of generating functions, arXiv:1509.08708 [math.CO], Sep 30 2015, p. 19.

Cf. A026007 (t=1), A026011 (t=2), A027346 (t=3).

nmax = 40; CoefficientList[Series[Product[(1+x^k)^(4*k), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Aug 17 2015 *)

a(n) ~ exp(2^(-2/3) * 3^(4/3) * Zeta(3)^(1/3) * n^(2/3)) * Zeta(3)^(1/6) / (2^(2/3) * 3^(1/3) * sqrt(Pi) * n^(2/3)). - Vaclav Kotesovec, Aug 17 2015

G.f.: exp(4*Sum_{k>=1} (-1)^(k+1)*x^k/(k*(1 - x^k)^2)). - Ilya Gutkovskiy, May 30 2018

A261389 Expansion of Product_{k>=1} ((1+x^k)/(1-x^k))^(3*k).

Original entry on oeis.org

1, 6, 30, 128, 486, 1704, 5604, 17484, 52206, 150118, 417696, 1128984, 2973476, 7650720, 19272432, 47616568, 115570014, 275921460, 648771802, 1503889488, 3439990344, 7770915816, 17349229908, 38306180052, 83694778556, 181052778078, 387976101432, 823939048560

Offset: 0

Vaclav Kotesovec, Aug 17 2015

nonn

Convolution of A255610 and A027346.

In general, if g.f. = Product_{k>=1} ((1+x^k)/(1-x^k))^(t*k) and t>=1, then a(n) ~ exp(t/12 + 3/2 * (7*t*Zeta(3)/2)^(1/3) * n^(2/3)) * t^(1/6 + t/36) * (7*Zeta(3))^(1/6 + t/36) / (A^t * 2^(2/3 + t/9) * sqrt(3*Pi) * n^(2/3 + t/36)), where Zeta(3) = A002117 and A = A074962 is the Glaisher-Kinkelin constant.

G. C. Greubel, Table of n, a(n) for n = 0..1000
Vaclav Kotesovec, A method of finding the asymptotics of q-series based on the convolution of generating functions, arXiv:1509.08708 [math.CO], Sep 30 2015, p. 19.

Cf. A156616 (t=1), A261386 (t=2).

Cf. A015128, A027346, A027906, A193427, A255610.

nmax = 40; CoefficientList[Series[Product[((1+x^k)/(1-x^k))^(3*k), {k, 1, nmax}], {x, 0, nmax}], x]

a(n) ~ exp(1/4 + 3/2 * (21*Zeta(3)/2)^(1/3) * n^(2/3)) * (7*Zeta(3)/3)^(1/4) / (2 * A^3 * sqrt(Pi) * n^(3/4)), where Zeta(3) = A002117 and A = A074962 is the Glaisher-Kinkelin constant.

A277938 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of Product_{j>=1} (1+x^j)^(j*k) in powers of x.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 2, 0, 1, 3, 5, 5, 0, 1, 4, 9, 14, 8, 0, 1, 5, 14, 28, 30, 16, 0, 1, 6, 20, 48, 72, 68, 28, 0, 1, 7, 27, 75, 141, 183, 145, 49, 0, 1, 8, 35, 110, 245, 396, 443, 298, 83, 0, 1, 9, 44, 154, 393, 751, 1058, 1026, 600, 142, 0, 1, 10, 54, 208

Offset: 0

Seiichi Manyama, Apr 11 2017

			Square array begins:
   1, 1,  1,  1,   1, ...
   0, 1,  2,  3,   4, ...
   0, 2,  5,  9,  14, ...
   0, 5, 14, 28,  48, ...
   0, 8, 30, 72, 141, ...

Seiichi Manyama, Antidiagonals n = 0..139, flattened

Columns k=0-4 give: A000007, A026007, A026011, A027346, A027906.
Rows n=0-3 give: A000012, A001477, A000096, A005586.
Main diagonal gives A270922.
Antidiagonal sums give A299167.
Cf. A276554, A279928.

G.f. of column k: Product_{j>=1} (1+x^j)^(j*k).

A279031 Expansion of Product_{k>0} 1/(1 + x^k)^(k*3).

Original entry on oeis.org

1, -3, 0, -1, 15, -3, 8, -42, 6, -83, 81, -39, 316, -90, 420, -603, 363, -1656, 625, -2556, 2877, -2599, 7818, -3483, 13886, -11049, 17040, -31493, 20196, -63876, 39244, -96453, 105891, -120431, 243333, -164100, 440873, -327387, 643968, -765115, 840207

Offset: 0

Seiichi Manyama, Apr 11 2017

sign

Seiichi Manyama, Table of n, a(n) for n = 0..10000

Product_{k>0} 1/(1 + x^k)^(k*m): A027346 (m=-3), A255528 (m=1), A278710 (m=2), this sequence (m=3), A279411 (m=4).

a(n) ~ (-1)^n * exp(-1/4 + 2^(-5/3) * 3^(4/3) * Zeta(3)^(1/3) * n^(2/3)) * A^3 * Zeta(3)^(1/12) / (2^(2/3) * 3^(5/12) * sqrt(Pi) * n^(7/12)), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Apr 13 2017

G.f.: exp(3*Sum_{k>=1} (-1)^k*x^k/(k*(1 - x^k)^2)). - Ilya Gutkovskiy, Mar 27 2018

cp's OEIS Frontend

A026007 Expansion of Product_{m>=1} (1 + q^m)^m; number of partitions of n into distinct parts, where n different parts of size n are available.

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A026011 Expansion of Product_{m>=1} (1 + q^m)^(2*m).

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A262878 Expansion of Product_{k>=1} (1+x^(3*k-1))^k.

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A262879 Expansion of Product_{k>=1} (1+x^(3*k-2))^k.

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A341385 Expansion of (-1 + Product_{k>=1} (1 + x^k)^k)^3.

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A027906 Expansion of Product_{m>=1} (1+q^m)^(4*m).

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A261389 Expansion of Product_{k>=1} ((1+x^k)/(1-x^k))^(3*k).

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A277938 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of Product_{j>=1} (1+x^j)^(j*k) in powers of x.

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