A022629 -id:A022629 - cp's OEIS frontend

A266891 Expansion of Product_{k>=1} (1 + k*x^k)^k.

1, 1, 4, 13, 29, 81, 188, 456, 1030, 2405, 5295, 11611, 25246, 53552, 113332, 235685, 486011, 990840, 2006567, 4018010, 7992003, 15768511, 30875424, 60060509, 116042548, 222817961, 425200270, 806991037, 1522748592, 2858792520, 5339457208, 9924370365

Offset: 0

Vaclav Kotesovec, Jan 05 2016

nonn

This sequence is obtained from the generalized Euler transform in A266964 by taking f(n) = -n, g(n) = -n. - Seiichi Manyama, Nov 18 2017

Seiichi Manyama, Table of n, a(n) for n = 0..10000 (terms 0..5000 from Vaclav Kotesovec)
Vaclav Kotesovec, Graph - The asymptotic ratio (200000 terms)

Cf. A022629, A026007, A032302, A261562, A266964, A304210, A304211.

nmax=50; CoefficientList[Series[Product[(1+k*x^k)^k, {k, 1, nmax}], {x, 0, nmax}], x]
(* More efficient program: *) nmax = 50; s = 1+x; Do[s*=Sum[Binomial[k, j] * k^j * x^(j*k), {j, 0, nmax/k}]; s = Take[Expand[s], Min[nmax + 1, Exponent[s, x] + 1]];, {k, 2, nmax}]; CoefficientList[s, x] (* Vaclav Kotesovec, Jan 07 2016 *)

a(0) = 1 and a(n) = (1/n) * Sum_{k=1..n} b(k)*a(n-k) where b(n) = Sum_{d|n} d*(-d)^(1+n/d). - Seiichi Manyama, Nov 18 2017

Conjecture: log(a(n)) ~ n^(2/3) * (2*log(3*n) - 3) / (4*3^(1/3)). - Vaclav Kotesovec, May 08 2018

A067553 Sum of products of terms in all partitions of n into odd parts.

Original entry on oeis.org

1, 1, 1, 4, 4, 9, 18, 25, 40, 76, 122, 178, 321, 472, 734, 1303, 1874, 2852, 4782, 6984, 10808, 17552, 25461, 38512, 61586, 90894, 135437, 213260, 312180, 463340, 728806, 1057468, 1562810, 2422394, 3511962, 5215671, 7985196, 11550542, 17022228, 25924746, 37638033

Offset: 0

Naohiro Nomoto, Jan 29 2002

a(0) = 1 as the empty product equals 1. [Joerg Arndt, Oct 06 2012]

Alois P. Heinz and Vaclav Kotesovec, Table of n, a(n) for n = 0..5000 (terms 0..1000 from Alois P. Heinz)

Cf. A006906, A022629, A000009.

b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
      b(n, i-1) +`if`(i>n or irem(i, 2)=0, 0, i*b(n-i, i))))
    end:
a:= n-> b(n$2):
seq(a(n), n=0..50);  # Alois P. Heinz, Sep 07 2014

b[n_, i_] := b[n, i] = If[n==0, 1, If[i<1, 0, b[n, i-1] + If[i>n || Mod[i, 2] == 0, 0, i*b[n-i, i]]]]; a[n_] := b[n, n]; Table[a[n], {n, 0, 50}] (* Jean-François Alcover, Apr 02 2015, after Alois P. Heinz *)
nmax = 40; CoefficientList[Series[Product[1/(1-(2*k-1)*x^(2*k-1)), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Dec 15 2015 *)

g(n):= if n=0 then 1 else if oddp(n)=true  then n else 0;
P(m,n):=if n=m then g(n) else sum(g(k)*P(k,n-k),k,m,n/2)+g(n);
a(n):=P(1,n);
makelist(a(n),n,0,27); /* Vladimir Kruchinin, Sep 06 2014 */

N=66; q='q+O('q^N);
gf= 1/ prod(n=1,N, (1-(2*n-1)*q^(2*n-1)) );
Vec(gf)
/* Joerg Arndt, Oct 06 2012 */

G.f.: 1/(Product_{k>=0} (1-(2*k+1)*x^(2*k+1)) ). - Vladeta Jovovic, May 09 2003
From Vaclav Kotesovec, Dec 15 2015: (Start)
a(n) ~ c * 3^(n/3), where
c = 28.8343667894061364904068323836801301428320806272385991... if mod(n,3) = 0
c = 28.4762018725001067057188975211539643762050439184376103... if mod(n,3) = 1
c = 28.3618072960214990676207117911869616961300790076910101... if mod(n,3) = 2.
(End)

Corrected a(0) from 0 to 1, Joerg Arndt, Oct 06 2012

A291698 a(n) = [x^n] Product_{k>=1} (1 + n*x^k).

Original entry on oeis.org

1, 1, 2, 12, 20, 55, 294, 497, 1224, 2520, 14410, 21912, 54300, 104286, 220710, 1105215, 1697552, 3839382, 7356762, 14873580, 26275620, 132112596, 188666126, 423247104, 772560600, 1535398150, 2632049290, 4975242048, 21273166572, 30649985160, 64824339630, 116604788800, 223181224992

Offset: 0

Ilya Gutkovskiy, Aug 30 2017

The number of partitions of n into distinct parts where each part can be colored in n different ways. For example, there are 4 partitions of 6 into distinct parts, namely 6, 5 + 1, 4 + 2 and 3 + 2 + 1; allowing for the colorings gives a(6) = 6 + 6*6 + 6*6 + 6*6*6 = 294. - Peter Bala, Aug 31 2017

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000 (terms 0..2000 from Robert Israel)

Main diagonal of A286957.

Cf. A022629, A124577, A292190, A292304.

seq(coeff(mul(1+n*x^k,k=1..n),x,n),n=0..50); # Robert Israel, Aug 30 2017

Table[SeriesCoefficient[Product[1 + n x^k, {k, 1, n}], {x, 0, n}], {n, 0, 32}]
Table[SeriesCoefficient[QPochhammer[-n, x]/(1 + n), {x, 0, n}], {n, 0, 32}]

a(n) = A286957(n,n).
a(n) == 0 (mod n); a(n) == n (mod n^2). - Peter Bala, Aug 31 2017
Conjecture: a(n) ~ exp(sqrt(2*(log(n)^2 + Pi^2/3)*n)) * (log(n)^2 + Pi^2/3)^(1/4) / (sqrt(Pi) * (2*n)^(5/4)). - Vaclav Kotesovec, Sep 15 2017

A092484 Expansion of Product_{m>=1} (1 + m^2*q^m).

Original entry on oeis.org

1, 1, 4, 13, 25, 77, 161, 393, 726, 2010, 3850, 7874, 16791, 31627, 69695, 139560, 255997, 482277, 986021, 1716430, 3544299, 6507128, 11887340, 21137849, 38636535, 70598032, 123697772, 233003286, 412142276, 711896765, 1252360770

Offset: 0

Jon Perry, Apr 04 2004

nonn

Sum of squares of products of terms in all partitions of n into distinct parts.

			The partitions of 6 into distinct parts are 6, 1+5, 2+4, 1+2+3, the corresponding squares of products are 36, 25, 64, 36 and their sum is a(6) = 161.

Alois P. Heinz, Table of n, a(n) for n = 0..10000

Cf. A022629, A077335, A265844, A285737, A292165.

Column k=2 of A292189.

b:= proc(n, i) option remember; (m->
      `if`(mn, 0, i^2*b(n-i, i-1)))))(i*(i+1)/2)
    end:
a:= n-> b(n$2):
seq(a(n), n=0..40);  # Alois P. Heinz, Sep 10 2017

Take[ CoefficientList[ Expand[ Product[1 + m^2*q^m, {m, 100}]], q], 31] (* Robert G. Wilson v, Apr 05 2005 *)

N=66; x='x+O('x^N); Vec(prod(n=1, N, 1+n^2*x^n)) \\ Seiichi Manyama, Sep 10 2017

G.f.: exp(Sum_{k>=1} Sum_{j>=1} (-1)^(k+1)*j^(2*k)*x^(j*k)/k). - Ilya Gutkovskiy, Jun 14 2018

Conjecture: log(a(n)) ~ sqrt(2*n) * (log(2*n) - 2). - Vaclav Kotesovec, Dec 27 2020

More terms from Robert G. Wilson v, Apr 05 2004

A022693 Expansion of Product_{m>=1} 1/(1 + m*q^m).

Original entry on oeis.org

1, -1, -1, -2, 2, -1, 4, -1, 18, -22, 12, -26, 67, -86, 42, -235, 432, -364, 506, -868, 1434, -2396, 2225, -3348, 10842, -11822, 8049, -24468, 36662, -40024, 69766, -96052, 171976, -278242, 251886, -419723, 885806, -998468, 1103660, -2381042, 4009539, -4478416, 6372514, -9913690

Offset: 0

N. J. A. Sloane

sign

Vaclav Kotesovec, Table of n, a(n) for n = 0..5000

Cf. A006906, A022629, A022661, A266971.

Coefficients(&*[1/(1+m*x^m):m in [1..40]])[1..40] where x is PolynomialRing(Integers()).1; // G. C. Greubel, Feb 25 2018

nmax = 40; CoefficientList[Series[Product[1/(1 + k*x^k), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Dec 15 2015 *)
nmax = 40; CoefficientList[Series[Exp[-Sum[(-1)^(j+1)*PolyLog[-j, x^j]/j, {j, 1, nmax}]], {x, 0, nmax}], x] (* Vaclav Kotesovec, Dec 15 2015 *)

m=50; q='q+O('q^m); Vec(prod(n=1,m,1/(1+n*q^n))) \\ G. C. Greubel, Feb 25 2018

From Vaclav Kotesovec, Dec 15 2015: (Start)
a(n) ~ (-1)^n * c * 3^(n/3), where
c = 2.0319526534291644237634198503666896166412... if mod(n,3) = 0
c = 1.8420902462379331740718256785549611496880... if mod(n,3) = 1
c = 1.6677871810486313099783673373643842640151... if mod(n,3) = 2.
(End)
From Benedict W. J. Irwin, Mar 19 2017: (Start)
Conjecture: a(n) = Sum_{i_1,i_2,i_3,...}[(-1)^(i_1+i_2+i_3+...)*Product_{n>0} n^i_n], where the sum is over all valid sequences of positive i_k such that i_1+2*i_2+3*i_3+4*i_4+...= n.
Examples: Setting i_k=0 unless explicitly mentioned.
  n=1, (i_1=1), a(1)= -1^1 = -1.
  n=2, (i_1=2) or (i_2=1), a(2) = 1^2 - 2^1 = -1.
  n=3, (i_1=3) or (i_1=1,i_2=1) or (i_3=1), a(3)=-1^3 + 1^1*2^1 - 3^1 = -2.
(End)

A325504 Product of products of parts over all strict integer partitions of n.

Original entry on oeis.org

1, 1, 2, 6, 12, 120, 1440, 40320, 1209600, 1567641600, 2633637888000, 13905608048640000, 5046067048690483200000, 5289893008483207348224000000, 1266933607446134946465526579200000000, 99304891373531545064656621572980736000000000000

Offset: 0

Gus Wiseman, May 07 2019

nonn

			The strict partitions of 5 are {(5), (4,1), (3,2)} with product a(5) = 5*4*1*3*2 = 120.
The sequence of terms together with their prime indices begins:
              1: {}
              1: {}
              2: {1}
              6: {1,2}
             12: {1,1,2}
            120: {1,1,1,2,3}
           1440: {1,1,1,1,1,2,2,3}
          40320: {1,1,1,1,1,1,1,2,2,3,4}
        1209600: {1,1,1,1,1,1,1,1,2,2,2,3,3,4}
     1567641600: {1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,3,3,4}
  2633637888000: {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,3,3,3,4,4}

Alois P. Heinz, Table of n, a(n) for n = 0..30

Cf. A000009, A006128, A007870 (non-strict version), A015723, A022629 (sum of products of parts), A066186, A066189, A066633, A246867, A325505, A325506, A325512, A325513, A325515.

a:= n-> mul(i, i=map(x-> x[], select(x->
        nops(x)=nops({x[]}), combinat[partition](n)))):
seq(a(n), n=0..15);  # Alois P. Heinz, Aug 03 2021
# second Maple program:
b:= proc(n, i) option remember; `if`(n=0, [1$2], `if`(i<1, [0, 1], ((f, g)->
     [f[1]+g[1], f[2]*g[2]*i^g[1]])(b(n, i-1), b(n-i, min(n-i, i-1)))))
    end:
a:= n-> b(n$2)[2]:
seq(a(n), n=0..15);  # Alois P. Heinz, Aug 03 2021

Table[Times@@Join@@Select[IntegerPartitions[n],UnsameQ@@#&],{n,0,10}]

A001222(a(n)) = A325515(n).

a(n) = A003963(A325506(n)).

A299164 Expansion of 1/(1 - xProduct_{k>=1} (1 + kx^k)).

Original entry on oeis.org

1, 1, 2, 5, 14, 35, 91, 233, 597, 1517, 3885, 9922, 25333, 64683, 165181, 421828, 1077277, 2750993, 7025168, 17940298, 45814165, 116996152, 298774246, 762982615, 1948434235, 4975732669, 12706571546, 32448880807, 82864981016, 211613009498, 540397935771, 1380018797044, 3524165721799

Offset: 0

Ilya Gutkovskiy, Feb 04 2018

nonn

Alois P. Heinz, Table of n, a(n) for n = 0..1000
N. J. A. Sloane, Transforms

Antidiagonal sums of A297321.

Cf. A022629, A067687, A299105, A299106, A299108, A299162, A299166, A299167.

nmax = 32; CoefficientList[Series[1/(1 - x Product[1 + k x^k, {k, 1, nmax}]), {x, 0, nmax}], x]

G.f.: 1/(1 - x*Product_{k>=1} (1 + k*x^k)).

a(0) = 1; a(n) = Sum_{k=1..n} A022629(k-1)*a(n-k).

A265758 Expansion of Product_{k>=1} ((1 + kx^k)/(1 - kx^k)).

Original entry on oeis.org

1, 2, 6, 16, 38, 88, 200, 428, 902, 1874, 3780, 7504, 14732, 28368, 54052, 101960, 189750, 349996, 640218, 1159624, 2084952, 3722008, 6593560, 11606268, 20308188, 35312170, 61065636, 105060200, 179795936, 306244136, 519291476, 876554860, 1473504846

Offset: 0

Vaclav Kotesovec, Dec 15 2015

nonn

Convolution of A022629 and A006906.

Vaclav Kotesovec, Table of n, a(n) for n = 0..5000

Cf. A006906, A015128, A022629, A022661, A022693, A261584.

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

a(n) ~ c * 3^(n/3), where
c = 28711548.45004804552683870974706458425598... if mod(n,3) = 0
c = 28711547.74098394497470795294574937283075... if mod(n,3) = 1
c = 28711547.58138731567204220029302329316039... if mod(n,3) = 2.

A325506 Product of Heinz numbers over all strict integer partitions of n.

Original entry on oeis.org

1, 2, 3, 30, 70, 2310, 180180, 21441420, 6401795400, 200984366583000, 41615822944675980000, 10515527757483671302380000, 4919824049783476260137727416400000, 5158181210492841550866520676965246284000000, 29776760895364738730693151196801613158042403043600000000

Offset: 0

Gus Wiseman, May 07 2019

nonn

a(n) is the product of row n of A246867 (squarefree numbers arranged by sum of prime indices).

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

			The strict integer partitions of 6 are {(6), (5,1), (4,2), (3,2,1)}, with Heinz numbers {13,22,21,30}, with product 13*22*21*30 = 180180, so a(6) = 180180.
The sequence of terms together with their prime indices begins:
                     1: {}
                     2: {1}
                     3: {2}
                    30: {1,2,3}
                    70: {1,3,4}
                  2310: {1,2,3,4,5}
                180180: {1,1,2,2,3,4,5,6}
              21441420: {1,1,2,2,3,4,4,5,6,7}
            6401795400: {1,1,1,2,2,3,3,4,5,5,6,7,8}
       200984366583000: {1,1,1,2,2,2,3,3,3,4,4,5,5,6,6,7,8,9}
  41615822944675980000: {1,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,5,5,6,6,7,7,8,9,10}

Cf. A003963, A006128, A015723, A022629, A056239, A112798, A147655, A215366, A246867, A325501, A325504, A325505, A325512, A325513.

Table[Times@@Prime/@(Join@@Select[IntegerPartitions[n],UnsameQ@@#&]),{n,0,15}]

a(n) = Product_{i = 1..A000009(n)} A246867(n,i).
A001222(a(n)) = A015723(n).
A056239(a(n)) = A066189(n).
A003963(a(n)) = A325504(n).
a(n) = A003963(A325505(n)).

A325513 Heinz number of the integer partition whose parts are the multiplicities in the multiset union of all strict integer partitions of n.

Original entry on oeis.org

1, 2, 2, 8, 8, 32, 144, 432, 2160, 27000, 582120, 7623000, 336936600, 6740402760, 543454231320, 57619849046760, 4683793138766280, 412882704970215480, 88171665744392750520, 12780536107937124847320, 2685589660883755945879560, 942036670625665177379096280

Offset: 0

Gus Wiseman, May 07 2019

nonn

Also the Heinz number of row n of A015716 (with zeros removed).

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

			The strict integer partitions of 6 are {(6), (5,1), (4,2), (3,2,1)}, with multiset union {1,1,2,2,3,4,5,6}, with multiplicities (2,2,1,1,1,1), so a(6) = prime(1)^4*prime(2)^2 = 144.
The sequence of terms together with their prime indices begins:
               1: {}
               2: {1}
               2: {1}
               8: {1,1,1}
               8: {1,1,1}
              32: {1,1,1,1,1}
             144: {1,1,1,1,2,2}
             432: {1,1,1,1,2,2,2}
            2160: {1,1,1,1,2,2,2,3}
           27000: {1,1,1,2,2,2,3,3,3}
          582120: {1,1,1,2,2,2,3,4,4,5}
         7623000: {1,1,1,2,2,3,3,3,4,5,5}
       336936600: {1,1,1,2,2,3,3,4,5,5,6,7}
      6740402760: {1,1,1,2,2,3,4,4,4,6,6,7,8}
    543454231320: {1,1,1,2,2,3,4,4,5,6,7,8,9,10}
  57619849046760: {1,1,1,2,2,3,4,5,5,6,8,9,10,11,12}

Alois P. Heinz, Table of n, a(n) for n = 0..172

Cf. A000009, A006128, A015716, A015723, A022629, A056239, A066633, A112798, A246867, A325500, A325504, A325506.

b:= proc(n, i) option remember;
      `if`(n>(i*(i+1)/2), 0, `if`(n=0, [1, 0], b(n, i-1)+
          (p-> p+[0, p[1]*x^i])(b(n-i, min(n-i, i-1)))))
    end:
a:= n-> (p-> mul((c-> `if`(c=0, 1, ithprime(c)))(
    coeff(p, x, i)), i=1..degree(p)))(b(n$2)[2]):
seq(a(n), n=0..21);  # Alois P. Heinz, Feb 23 2024

Table[Times@@Prime/@Length/@Split[Sort[Join@@Select[IntegerPartitions[n],UnsameQ@@#&]]],{n,0,15}]

a(n) = A181819(A003963(A325505(n))).

A056239(a(n)) = A015723(n).

cp's OEIS Frontend

A266891 Expansion of Product_{k>=1} (1 + k*x^k)^k.

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A067553 Sum of products of terms in all partitions of n into odd parts.

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A291698 a(n) = [x^n] Product_{k>=1} (1 + n*x^k).

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A092484 Expansion of Product_{m>=1} (1 + m^2*q^m).

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A022693 Expansion of Product_{m>=1} 1/(1 + m*q^m).

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A325504 Product of products of parts over all strict integer partitions of n.

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A299164 Expansion of 1/(1 - x*Product_{k>=1} (1 + k*x^k)).

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A299164 Expansion of 1/(1 - xProduct_{k>=1} (1 + kx^k)).

A265758 Expansion of Product_{k>=1} ((1 + kx^k)/(1 - kx^k)).