A219560 -id:A219560 - cp's OEIS frontend

A219585 Number A(n,k) of k-partite partitions of {n}^k into distinct k-tuples; square array A(n,k), n>=0, k>=0, read by antidiagonals.

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 5, 5, 2, 1, 1, 15, 40, 17, 2, 1, 1, 52, 457, 364, 46, 3, 1, 1, 203, 6995, 14595, 2897, 123, 4, 1, 1, 877, 136771, 937776, 407287, 21369, 323, 5, 1, 1, 4140, 3299218, 88507276, 107652681, 10200931, 148257, 809, 6, 1

Offset: 0

Alois P. Heinz, Nov 23 2012

A(n,k) is the number of factorizations of m^n into distinct factors where m is a product of k distinct primes. A(2,2) = 5: (2*3)^2 = 36 has 5 factorizations into distinct factors: 36, 3*12, 4*9, 2*18, 2*3*6.

			A(1,3) = 5: [(1,1,1)], [(1,1,0),(0,0,1)], [(1,0,1),(0,1,0)], [(1,0,0),(0,1,0),(0,0,1)], [(0,1,1),(1,0,0)].
A(3,2) = 17: [(3,3)], [(3,0),(0,3)], [(3,2),(0,1)], [(2,3),(1,0)], [(3,1),(0,2)], [(2,2),(1,1)], [(1,3),(2,0)], [(2,1),(1,2)], [(2,1),(1,1),(0,1)], [(3,0),(0,2),(0,1)], [(2,2),(1,0),(0,1)], [(2,1),(0,2),(1,0)], [(1,2),(2,0),(0,1)], [(1,2),(1,1),(1,0)], [(0,3),(2,0),(1,0)], [(2,0),(1,1),(0,2)], [(2,0),(0,2),(1,0),(0,1)].
Square array A(n,k) begins:
  1,  1,   1,      1,          1,            1,         1, ...
  1,  1,   2,      5,         15,           52,       203, ...
  1,  1,   5,     40,        457,         6995,    136771, ...
  1,  2,  17,    364,      14595,       937776,  88507276, ...
  1,  2,  46,   2897,     407287,    107652681,  ...
  1,  3, 123,  21369,   10200931,  10781201973,  ...
  1,  4, 323, 148257,  233051939,  ...
  1,  5, 809, 970246, 4909342744,  ...

Andrew Howroyd, Table of n, a(n) for n = 0..209

Columns k=0..5 give: A000012, A000009, A219554, A219560, A219561, A219565.
Rows n=0..3 give: A000012, A000110, A094574, A319591.
Cf. A188445, A219727 (partitions of {n}^k into k-tuples), A318286.

f[n_, k_] := f[n, k] = 1/2 Product[Sum[O[x[j]]^(n+1), {j, 1, k}]+1+ Product[x[j]^i[j], {j, 1, k}], Evaluate[Sequence @@ Table[{i[j], 0, n}, {j, 1, k}]]];
a[0, ] = a[, 0] = 1; a[n_, k_] := SeriesCoefficient[f[n, k], Sequence @@ Table[{x[j], 0, n}, {j, 1, k}]];
Table[Print[a[n-k, k]]; a[n-k, k], {n, 0, 9}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Dec 11 2013, updated Sep 16 2019 *)

EulerT(v)={Vec(exp(x*Ser(dirmul(v,vector(#v,n,1/n))))-1, -#v)}
D(p, n, k)={my(v=vector(n)); for(i=1, #p, v[p[i]]++); EulerT(v)[n]^k/prod(i=1, #v, i^v[i]*v[i]!)}
T(n, k)={my(m=n*k+1, q=Vec(exp(intformal(O(x^m) - x^n/(1-x)))/(1+x))); if(n==0, 1, (-1)^m*sum(j=0, m, my(s=0); forpart(p=j, s+=(-1)^#p*D(p, n, k), [1, n]); s*q[#q-j])/2)} \\ Andrew Howroyd, Dec 16 2018

A(n,k) = [(Product_{j=1..k} x_j)^n] 1/2 * Product_{i_1,...,i_k>=0} (1+Product_{j=1..k} x_j^i_j).

A219554 Number of bipartite partitions of (n,n) into distinct pairs.

Original entry on oeis.org

1, 2, 5, 17, 46, 123, 323, 809, 1966, 4660, 10792, 24447, 54344, 118681, 254991, 539852, 1127279, 2323849, 4733680, 9535079, 19005282, 37507802, 73333494, 142112402, 273092320, 520612305, 984944052, 1849920722, 3450476080, 6393203741, 11770416313, 21538246251

Offset: 0

Alois P. Heinz, Nov 22 2012

Number of factorizations of p^n*q^n into distinct factors where p, q are distinct primes.
From Vaclav Kotesovec, Feb 05 2016: (Start)
Formula (15) in the article by S. M. Luthra: "Partitions of bipartite numbers when the summands are unequal", p. 376, is incorrect. The similar error is also in the article by F. C. Auluck: "On partitions of bipartite numbers" (see A002774).
The correct formula (15) is q(m, n) ~ c/(2*sqrt(3)*Pi) * exp(3*c*(m*n)^(1/3) + 3*d*(m^(2/3)/n^(1/3) + n^(2/3)/m^(1/3)) - 3*log(2)/4 + (m/n + n/m)*log(2)/12 + 3*d^2/c - 3*d^2*(m/n + n/m)/c - 2*log(m*n)/3), where m and n are of the same order, c = (3/4*Zeta(3))^(1/3), d = Zeta(2)/(12*c).
If m = n then q(m,n) = a(n).
For the asymptotic formula for fixed m see A054242.
(End)

			a(0) = 1: [].
a(1) = 2: [(1,1)], [(1,0),(0,1)].
a(2) = 5: [(2,2)], [(2,1),(0,1)], [(2,0),(0,2)], [(1,2),(1,0)], [(1,1),(1,0),(0,1)].

Alois P. Heinz and Vaclav Kotesovec, Table of n, a(n) for n = 0..400 (terms 0..100 from Alois P. Heinz)
S. M. Luthra, Partitions of bipartite numbers when the summands are unequal, Proceedings of the Indian National Science Academy, vol. 23, 1957, issue 5A, p. 370-376. [broken link]

Column k=2 of A219585.
Cf. A002774, A219560, A219561, A219565.
Cf. A054242, A000009, A036469, A268345, A268346, A268347, A268348.

(* This program is not convenient for a large number of terms *)
a[n_] := If[n == 0, 1, (1/2) Coefficient[Product[O[x]^(n+1) + O[y]^(n+1) + (1 + x^i y^j ), {i, 0, n}, {j, 0, n}] // Normal, (x y)^n]];
a /@ Range[0, 31] (* Jean-François Alcover, Jun 26 2013, updated Sep 16 2019 *)
nmax = 20; p = 1; Do[Do[p = Expand[p*(1 + x^i*y^j)]; If[i*j != 0, p = Select[p, (Exponent[#, x] <= nmax) && (Exponent[#, y] <= nmax) &]], {i, 0, nmax}], {j, 0, nmax}]; p = Select[p, Exponent[#, x] == Exponent[#, y] &]; Flatten[{1, Table[Coefficient[p, x^n*y^n]/2, {n, 1, nmax}]}] (* Vaclav Kotesovec, Jan 15 2016 *)

a(n) = [x^n*y^n] 1/2 * Product_{i,j>=0} (1+x^i*y^j).
a(n) = A054242(2*n,n) = A201377(n,n).
a(n) ~ Zeta(3)^(1/3) * exp(3^(4/3) * Zeta(3)^(1/3) * n^(2/3) / 2^(2/3) + Pi^2 * n^(1/3) / (6^(4/3) * Zeta(3)^(1/3)) - Pi^4/(1296*Zeta(3))) / (2^(9/4) * 3^(1/6) * Pi * n^(4/3)). - Vaclav Kotesovec, Jan 31 2016

A280473 G.f.: Product_{i>=1, j>=1, k>=1} (1 + x^(ijk)).

Original entry on oeis.org

1, 1, 3, 6, 12, 21, 43, 70, 127, 215, 364, 591, 989, 1562, 2515, 3954, 6194, 9538, 14754, 22349, 33926, 50910, 76102, 112721, 166747, 244205, 356984, 518344, 749924, 1078711, 1547668, 2207418, 3140135, 4446572, 6276657, 8823776, 12371487, 17275879, 24061878

Offset: 0

Vaclav Kotesovec, Jan 04 2017

nonn

Vaclav Kotesovec, 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.

Cf. A007425, A107742, A174465, A219560, A280486.

nmax = 50; CoefficientList[Series[Product[(1+x^(i*j*k)), {i, 1, nmax}, {j, 1, nmax/i}, {k, 1, nmax/i/j}], {x, 0, nmax}], x]
nmax = 50; A007425 = Table[Sum[DivisorSigma[0, d], {d, Divisors[n]}], {n, 1, nmax}]; s = 1 + x; Do[s *= Sum[Binomial[A007425[[k]], j]*x^(j*k), {j, 0, nmax/k}]; s = Expand[s]; s = Take[s, Min[nmax + 1, Exponent[s, x] + 1, Length[s]]];, {k, 2, nmax}]; Take[CoefficientList[s, x], nmax + 1] (* Vaclav Kotesovec, Aug 30 2018 *)

G.f.: Product_{k>=1} (1 + x^k)^tau_3(k), where tau_3() = A007425. - Ilya Gutkovskiy, May 22 2018

A219561 Number of 4-partite partitions of (n,n,n,n) into distinct quadruples.

Original entry on oeis.org

1, 15, 457, 14595, 407287, 10200931, 233051939, 4909342744, 96272310302, 1771597038279, 30795582025352, 508466832109216, 8011287089600483, 120926718707154007, 1754672912487450236, 24547188914867491083, 331937179344717327559, 4348524173437743243649, 55300773426746984710983

Offset: 0

Alois P. Heinz, Nov 23 2012

nonn

Number of factorizations of (p*q*r*s)^n into distinct factors where p, q, r, s are distinct primes.

			a(0) = 1: [].
a(1) = 15: [(1,0,0,0),(0,1,0,0),(0,0,1,0),(0,0,0,1)], [(0,0,1,1),(1,0,0,0),(0,1,0,0)], [(0,1,0,1),(1,0,0,0),(0,0,1,0)], [(0,1,1,0),(1,0,0,0),(0,0,0,1)], [(1,0,0,1),(0,1,0,0),(0,0,1,0)], [(1,0,0,1),(0,1,1,0)], [(1,0,1,0),(0,1,0,0),(0,0,0,1)], [(1,0,1,0),(0,1,0,1)], [(1,1,0,0),(0,0,1,0),(0,0,0,1)], [(1,1,0,0),(0,0,1,1)], [(0,1,1,1),(1,0,0,0)], [(1,0,1,1),(0,1,0,0)], [(1,1,0,1),(0,0,1,0)], [(1,1,1,0),(0,0,0,1)], [(1,1,1,1)].

Column k=4 of A219585.

Cf. A002774, A219554, A219560, A219565.

a[n_] := If[n == 0, 1, (1/2) Coefficient[Product[O[w]^(n+1) + O[x]^(n+1) + O[y]^(n+1) + O[z]^(n+1) + (1 + w^i x^j y^k z^m), {i, 0, n}, {j, 0, n}, {k, 0, n}, {m, 0, n}] // Normal, (w x y z)^n]];
Table[Print[n]; a[n], {n, 0, 12}] (* Jean-François Alcover, Sep 16 2019 *)

a(n) = [(w*x*y*z)^n] 1/2 * Product_{i,j,k,m>=0} (1+w^i*x^j*y^k*z^m).

a(9) from Alois P. Heinz, Oct 15 2014

a(10)-a(18) from Andrew Howroyd, Dec 17 2018

A219565 Number of 5-partite partitions of (n,n,n,n,n) into distinct quintuples.

Original entry on oeis.org

1, 52, 6995, 937776, 107652681, 10781201973, 958919976957, 76861542428397, 5620227129073491, 378709513816248475, 23713852762539359688, 1389561695379881634055, 76647024053735036288641, 3999799865715906390697377, 198328846122797866982616805, 9379277765981012067789260214

Offset: 0

Alois P. Heinz, Nov 23 2012

nonn

Number of factorizations of (p*q*r*s*t)^n into distinct factors where p, q, r, s, t are distinct primes.

Column k=5 of A219585.

Cf. A002774, A219554, A219560, A219561.

a[n_] := a[n] = If[n == 0, 1, (1/2) Coefficient[Product[O[v]^(n+1) + O[w]^(n+1) + O[x]^(n+1) + O[y]^(n+1) + O[z]^(n+1) + (1 + v^i w^j x^k y^l z^m), {i, 0, n}, {j, 0, n}, {k, 0, n}, {l, 0, n}, {m, 0, n}] // Normal, (v w x y z)^n]];
Table[Print[n, " ", a[n]]; a[n], {n, 0, 7}] (* Jean-François Alcover, Sep 24 2019 *)

a(n) = [(v*w*x*y*z)^n] 1/2 * Product_{h,i,j,k,m>=0} (1+v^h*w^i*x^j*y^k*z^m).

a(6) from Alois P. Heinz, Sep 25 2014

a(7)-a(15) from Andrew Howroyd, Dec 16 2018

A219678 Number of tripartite partitions of (n,n,n) into triples.

Original entry on oeis.org

1, 5, 66, 686, 6721, 58616, 476781, 3608348, 25781989, 174810494, 1132328205, 7037425172, 42140788751, 243918472743, 1368647208107, 7462686474948, 39626100989332, 205283558905562, 1039263967957447, 5149048724566723, 24998922141116056, 119073277412589351

Offset: 0

Alois P. Heinz, Nov 26 2012

nonn

a(n) is also the number of factorizations of m^n where m is a product of 3 distinct primes. a(1) = 5: (2*3*5)^1 = 30 has 5 factorizations: 30, 5*6, 3*10, 2*3*5, 2*15.

			a(1) = 5: [(1,1,1)], [(1,1,0),(0,0,1)], [(1,0,1),(0,1,0)], [(1,0,0),(0,1,0),(0,0,1)], [(0,1,1),(1,0,0)].

Sean A. Irvine, Table of n, a(n) for n = 0..29

Column k=3 of A219727.

Cf. A219560.

More terms from Sean A. Irvine, Aug 14 2014

cp's OEIS Frontend

A219585 Number A(n,k) of k-partite partitions of {n}^k into distinct k-tuples; square array A(n,k), n>=0, k>=0, read by antidiagonals.

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A219554 Number of bipartite partitions of (n,n) into distinct pairs.

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A280473 G.f.: Product_{i>=1, j>=1, k>=1} (1 + x^(i*j*k)).

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A219561 Number of 4-partite partitions of (n,n,n,n) into distinct quadruples.

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A219565 Number of 5-partite partitions of (n,n,n,n,n) into distinct quintuples.

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A219678 Number of tripartite partitions of (n,n,n) into triples.

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A280473 G.f.: Product_{i>=1, j>=1, k>=1} (1 + x^(ijk)).