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.

Showing 1-4 of 4 results.

A144064 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is Euler transform of (j->k).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 2, 0, 1, 3, 5, 3, 0, 1, 4, 9, 10, 5, 0, 1, 5, 14, 22, 20, 7, 0, 1, 6, 20, 40, 51, 36, 11, 0, 1, 7, 27, 65, 105, 108, 65, 15, 0, 1, 8, 35, 98, 190, 252, 221, 110, 22, 0, 1, 9, 44, 140, 315, 506, 574, 429, 185, 30, 0, 1, 10, 54, 192, 490, 918, 1265, 1240, 810, 300, 42, 0
Offset: 0

Views

Author

Alois P. Heinz, Sep 09 2008

Keywords

Comments

A(n,k) is also the number of partitions of n into parts of k kinds.
In general, column k > 0 is asymptotic to k^((k+1)/4) * exp(Pi*sqrt(2*k*n/3)) / (2^((3*k+5)/4) * 3^((k+1)/4) * n^((k+3)/4)) * (1 - (Pi*k^(3/2)/(24*sqrt(6)) + sqrt(3)*(k+1)*(k+3)/(8*Pi*sqrt(2*k))) / sqrt(n)). - Vaclav Kotesovec, Feb 28 2015, extended Jan 16 2017
When k is a prime power greater than 1, A(n,k) is the number of conjugacy classes of n X n matrices over a field with k elements that contain an upper-triangular matrix. - Geoffrey Critzer, Nov 11 2022

Examples

			Square array begins:
  1,   1,   1,   1,   1,   1, ...
  0,   1,   2,   3,   4,   5, ...
  0,   2,   5,   9,  14,  20, ...
  0,   3,  10,  22,  40,  65, ...
  0,   5,  20,  51, 105, 190, ...
  0,   7,  36, 108, 252, 506, ...
		

Crossrefs

Cf. A082556 (k=30), A082557 (k=32), A082558 (k=48), A082559 (k=64).
Rows n=0-4 give: A000012, A001477, A000096, A006503, A006504.
Main diagonal gives A008485.
Antidiagonal sums give A067687.

Programs

  • Julia
    # DedekindEta is defined in A000594.
    A144064Column(k, len) = DedekindEta(len, -k)
    for n in 0:8 A144064Column(n, 6) |> println end # Peter Luschny, Mar 10 2018
    
  • Maple
    with(numtheory): etr:= proc(p) local b; b:= proc(n) option remember; `if`(n=0, 1, add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n)/n) end end: A:= (n,k)-> etr(j->k)(n): seq(seq(A(n, d-n), n=0..d), d=0..14);
  • Mathematica
    a[0, ] = 1; a[, 0] = 0; a[n_, k_] := SeriesCoefficient[ Product[1/(1 - x^j)^k, {j, 1, n}], {x, 0, n}]; Table[a[n - k, k], {n, 0, 11}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Dec 06 2013 *)
    etr[p_] := Module[{b}, b[n_] := b[n] = If[n==0, 1, Sum[Sum[d*p[d], {d, Divisors[j]} ]*b[n-j], {j, 1, n}]/n]; b]; A[n_, k_] := etr[k&][n]; Table[A[n, d-n], {d, 0, 14}, {n, 0, d}] // Flatten (* Jean-François Alcover, Mar 30 2015, after Alois P. Heinz *)
  • PARI
    Mat(apply( {A144064_col(k,nMax=9)=Col(1/eta('x+O('x^nMax))^k,nMax)}, [0..9])) \\ M. F. Hasler, Aug 04 2024

Formula

G.f. of column k: Product_{j>=1} 1/(1-x^j)^k.
A(n,k) = Sum_{i=0..k} binomial(k,i) * A060642(n,k-i):

A341227 Expansion of (-1 + Product_{k>=1} 1 / (1 - x^k))^8.

Original entry on oeis.org

1, 16, 136, 824, 4004, 16608, 61076, 204200, 631714, 1831752, 5027312, 13159104, 33049090, 80030808, 187613348, 427201176, 947520103, 2051989360, 4347996772, 9030416704, 18412343832, 36905322248, 72807201940, 141525042736, 271321432489, 513454659312
Offset: 8

Views

Author

Ilya Gutkovskiy, Feb 07 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<2, `if`(n=0, 1-k, combinat[
          numbpart](n)), (q-> add(b(j, q)*b(n-j, k-q), j=0..n))(iquo(k, 2)))
        end:
    a:= n-> b(n, 8):
    seq(a(n), n=8..33);  # Alois P. Heinz, Feb 07 2021
  • Mathematica
    nmax = 33; CoefficientList[Series[(-1 + Product[1/(1 - x^k), {k, 1, nmax}])^8, {x, 0, nmax}], x] // Drop[#, 8] &

A193427 G.f.: Product_{k>=1} 1/(1-x^k)^(8*k).

Original entry on oeis.org

1, 8, 52, 272, 1266, 5344, 20992, 77584, 272727, 917936, 2975492, 9328736, 28391410, 84122688, 243265848, 688008048, 1906476351, 5184024112, 13851270944, 36409640400, 94255399886, 240529147072, 605574003464, 1505340071744
Offset: 0

Views

Author

Martin Y. Veillette, Jul 28 2011

Keywords

Comments

Previous name was: Number of plane partitions of n into parts of 8 kinds.
In general, if g.f. = Product_{k>=1} 1/(1-x^k)^(m*k) and m > 0, then a(n) ~ 2^(m/36 - 1/3) * exp(m/12 + 3 * 2^(-2/3) * m^(1/3) * zeta(3)^(1/3) * n^(2/3)) * (m*zeta(3))^(m/36 + 1/6) / (A^m * sqrt(3*Pi) * n^(m/36 + 2/3)), where A = A074962 = 1.2824271291... is the Glaisher-Kinkelin constant. - Vaclav Kotesovec, Mar 01 2015

Crossrefs

Cf. A000219 (m=1), A161870 (m=2), A255610 (m=3), A255611 (m=4), A255612 (m=5), A255613 (m=6), A255614 (m=7).
Column k=8 of A255961.

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=0, 1, 8*add(
          a(n-j)*numtheory[sigma][2](j), j=1..n)/n)
        end:
    seq(a(n), n=0..30);  # Alois P. Heinz, Mar 11 2015
  • Mathematica
    ANS = Block[{kmax = 50},
      Coefficient[
       Series[Product[1/(1 - x^k)^(8 k), {k, 1, kmax}], {x, 0, kmax}], x,
       Range[0, kmax]]]
    (* Second program: *)
    a[n_] := a[n] = If[n==0, 1, 8*Sum[a[n-j]*DivisorSigma[2, j], {j, 1, n}]/n]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Feb 07 2017, after Alois P. Heinz *)
  • PARI
    Vec(prod(k=1,100\2,(1-x^k)^(-8*k),1+O(x^101))) \\ Charles R Greathouse IV, Aug 09 2011

Formula

G.f.: Product_{k>=1} (1-x^k)^(-8*k).
a(n) ~ 2^(19/18) * zeta(3)^(7/18) * exp(2/3 + 3 * 2^(1/3) * zeta(3)^(1/3) * n^(2/3)) / (A^8 * sqrt(3*Pi) * n^(8/9)), where A = A074962 = 1.2824271291... is the Glaisher-Kinkelin constant and zeta(3) = A002117 = 1.202056903... . - Vaclav Kotesovec, Feb 28 2015
G.f.: exp(8*Sum_{k>=1} x^k/(k*(1 - x^k)^2)). - Ilya Gutkovskiy, May 29 2018
Euler transform of 8*k. - Georg Fischer, Aug 15 2020

Extensions

New name from Vaclav Kotesovec, Mar 12 2015

A339323 Dirichlet g.f.: Product_{k>=2} 1 / (1 - k^(-s))^8.

Original entry on oeis.org

1, 8, 8, 44, 8, 72, 8, 192, 44, 72, 8, 424, 8, 72, 72, 726, 8, 424, 8, 424, 72, 72, 8, 1960, 44, 72, 192, 424, 8, 712, 8, 2464, 72, 72, 72, 2620, 8, 72, 72, 1960, 8, 712, 8, 424, 424, 72, 8, 7768, 44, 424, 72, 424, 8, 1960, 72, 1960, 72, 72, 8, 4456, 8, 72, 424
Offset: 1

Views

Author

Ilya Gutkovskiy, Nov 30 2020

Keywords

Comments

Number of factorizations of n into factors (greater than 1) of 8 kinds.

Crossrefs

Formula

a(p^k) = A023007(k) for prime p.
Showing 1-4 of 4 results.