cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A096597 Triangle read by rows: T[n,m] = number of plane partitions of n whose 3-dimensional Ferrers plot just fits inside an m X m X m box, i.e., with Max[parts, rows, columns] = m.

Original entry on oeis.org

1, 0, 3, 0, 3, 3, 0, 4, 6, 3, 0, 3, 12, 6, 3, 0, 3, 21, 15, 6, 3, 0, 1, 31, 30, 15, 6, 3, 0, 1, 42, 60, 33, 15, 6, 3, 0, 0, 54, 102, 69, 33, 15, 6, 3, 0, 0, 64, 175, 132, 72, 33, 15, 6, 3, 0, 0, 73, 270, 246, 141, 72, 33, 15, 6, 3, 0, 0, 81, 417, 432, 276, 144, 72, 33, 15, 6, 3, 0, 0, 83
Offset: 1

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Author

Wouter Meeussen, Aug 14 2004

Keywords

Comments

Row sums equal A000219 (plane partitions).
Conjecture: the last (floor(n/2)) terms of each row read backwards are 3*A091360 (partial sums of A000219).
Björner & Stanley (2010) give in eq.(3.7) MacMahon's generating function pp(r,s,t) for the number of plane partitions with rows <= r, columns <= s, parts <= t. For r = s = t = m, it simplifies to the g.f. f(m) given in formula. A g.f. for column m of this table is then f(m) - f(m-1). - M. F. Hasler, Sep 26 2018

Examples

			The table starts:
  n : T[n,1..n]
  1 : [1]
  2 : [0, 3]
  3 : [0, 3,  3]
  4 : [0, 4,  6,   3]
  5 : [0, 3, 12,   6,  3]
  6 : [0, 3, 21,  15,  6,  3]
  7 : [0, 1, 31,  30, 15,  6,  3]
  8 : [0, 1, 42,  60, 33, 15,  6, 3]
  9 : [0, 0, 54, 102, 69, 33, 15, 6, 3]
etc.
T[5,2] = 3 counts the plane partitions {{2,1},{2}}, {{2,1},{1,1}} and {{2,2},{1}}.
		

Crossrefs

Programs

  • Mathematica
    (* see A089924 for "planepartitions[]" *) Table[Rest@CoefficientList[Plus@@(x ^ Max[Flatten[ # ], Length[ # ], Max[Length/@# ]]&/@ planepartitions[n]), x], {n, 19}]
  • PARI
    A096597_row(n,c=vector(n))={for(i=1,#n=PlanePartitions(n),c[vecmax([#n[i], #n[i][1], n[i][1][1]])]++);c} \\ See A091298 for PlanePartitions().
    {A096597(n,m,x=(O('x^n)+1)*'x,f(r)=prod(k=1,2*r-1,((1-x^(k+r))/(1-x^k))^min(k,2*r-k)))=polcoeff(f(m)-f(m-1),n)} \\ Replace "polcoeff(...,n)" by "Vec(...)" to get the whole column m up to row n (for "Vec(...,-n)", padded with leading 0's). - M. F. Hasler, Sep 26 2018

Formula

k-th column is CoefficientList[Series[qMacMahon[k]-qMacMahon[k-1], {q, 0, 3^k}], q] with qMacMahon[n_Integer]:=Product[qan[i+j+k-1]/qan[i+j+k-2], {i, n}, {j, n}, {k, n}] and qan[n_]:=(q^n-1)/(q-1). - Wouter Meeussen, Aug 28 2004
From M. F. Hasler, Sep 26 2018: (Start)
G.f. of column m: f(m)-f(m-1), where f(m) = Product_{k=1..2*m-1} ((1-X^(k+m))/(1-X^k))^min(k,2*m-k).
From the definition, we have T[n,m] = 0 if n > m^3.
Columns and reversed rows converge to 3*A091360: T[m+k,m] = T[2m,2m-k] = 3*A091360(k) for 0 <= k < m-1. (End)

Extensions

Edited by M. F. Hasler, Sep 24 2018

A277963 G.f.: 1/(1+x) * Product_{k>=1} 1/(1-x^k)^k.

Original entry on oeis.org

1, 0, 3, 3, 10, 14, 34, 52, 108, 174, 326, 533, 946, 1539, 2628, 4251, 7046, 11288, 18313, 29017, 46261, 72533, 113942, 176841, 274353, 421680, 647065, 985593, 1497641, 2261971, 3406992, 5105317, 7628112, 11346861, 16829094, 24861952, 36623009, 53756775
Offset: 0

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Author

Vaclav Kotesovec, Nov 06 2016

Keywords

Comments

Convolution of A000219 and A033999.

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[1/(1+x)*Product[1/(1-x^k)^k, {k, 1, 50}], {x, 0, 50}], x]

Formula

a(n) = Sum_{k=0..n} (-1)^(n-k)*A000219(k).
a(n) ~ Zeta(3)^(7/36) * exp(3 * Zeta(3)^(1/3) * (n/2)^(2/3) + 1/12) / (A * sqrt(3*Pi) * 2^(47/36) * n^(25/36)), where A = A074962 is the Glaisher-Kinkelin constant.

A291552 Expansion of (1/(1 - x))*Product_{k>=1} 1/(1 - x^k)^p(k), where p(k) is the number of partitions of k (A000041).

Original entry on oeis.org

1, 2, 5, 11, 25, 52, 110, 221, 444, 868, 1685, 3212, 6082, 11361, 21071, 38693, 70570, 127670, 229557, 409963, 728069, 1285522, 2258318, 3947115, 6867238, 11893648, 20513199, 35235429, 60292928, 102787903, 174620017, 295644893, 498931699, 839367287, 1407864040, 2354559426, 3926878130
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 30 2017

Keywords

Comments

Partial sums of A001970.

Examples

			Equivalently (Cayley), a(n) = total number of 2-dimensional partitions of all nonnegative integers <= n.
a(3) = 11 because we have:
0...1...2.11.1...3.21.2.111.11.1
.............1........1.....1..1
...............................1
and 1 + 1 + 3 + 6 = 11.
		

Crossrefs

Programs

  • Maple
    with(numtheory): with(combinat):
    b:= proc(n) option remember; `if`(n=0, 1, add(add(d*
          numbpart(d), d=divisors(j))*b(n-j), j=1..n)/n)
        end:
    a:= proc(n) option remember; b(n)+`if`(n>0, a(n-1), 0) end:
    seq(a(n), n=0..40);  # Alois P. Heinz, Sep 11 2017
  • Mathematica
    nmax = 36; CoefficientList[Series[1/(1 - x) Product[1/(1 - x^k)^PartitionsP[k], {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: (1/(1 - x))*Product_{k>=1} 1/(1 - x^k)^p(k), where p(k) = [x^k] Product_{k>=1} 1/(1 - x^k).

A309267 Expansion of (1 + x) * Product_{k>=1} 1/(1 - x^k)^k.

Original entry on oeis.org

1, 2, 4, 9, 19, 37, 72, 134, 246, 442, 782, 1359, 2338, 3964, 6652, 11046, 18176, 29631, 47935, 76931, 122608, 194072, 305269, 477258, 741977, 1147227, 1764778, 2701403, 4115892, 6242846, 9428575, 14181272, 21245738, 31708402, 47150928, 69867001, 103176007, 151864745, 222821779
Offset: 0

Views

Author

Ilya Gutkovskiy, Jul 20 2019

Keywords

Crossrefs

Programs

  • Maple
    G:= (1+x)/mul((1-x^k)^k,k=1..100):
    S:= series(G,x,101):
    seq(coeff(S,x,j),j=0..100); # Robert Israel, Dec 01 2020
  • Mathematica
    nmax = 38; CoefficientList[Series[(1 + x) Product[1/(1 - x^k)^k, {k, 1, nmax}], {x, 0, nmax}], x]
    a[0] = 1; a[n_] := a[n] = Sum[DivisorSigma[2, k] a[n - k], {k, 1, n}]/n; Table[a[n] + a[n - 1], {n, 0, 38}]

Formula

a(n) = A000219(n) + A000219(n-1).
a(n) ~ Zeta(3)^(7/36) * 2^(25/36) * exp(3 * Zeta(3)^(1/3) * (n/2)^(2/3) + 1/12) / (A * sqrt(3*Pi) * n^(25/36)), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Jul 20 2019
Previous Showing 11-14 of 14 results.