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 1-3 of 3 results.

A324402 a(n) = Product_{i=1..n, j=1..n} (2*i + j).

Original entry on oeis.org

1, 3, 360, 6350400, 36212520960000, 117563342374788710400000, 337905477880065368190647009280000000, 1234818479230749311108497004714406224855040000000000, 7795494015765035913020359514023640290443493305037073940480000000000000
Offset: 0

Views

Author

Vaclav Kotesovec, Feb 26 2019

Keywords

Crossrefs

Programs

  • Maple
    f:= n -> mul((2*i+n)!/(2*i)!,i=1..n):
    map(f, [$0..10]); # Robert Israel, Feb 27 2019
  • Mathematica
    Table[Product[2*i+j, {i, 1, n}, {j, 1, n}], {n, 1, 10}]

Formula

a(n) ~ sqrt(A/Pi) * 3^(9*n*(n+1)/4 + 11/24) * n^(n^2 - 11/24) / (2^(n^2 + 3*n/2 + 17/24) * exp(3*n^2/2 + 1/24)), where A is the Glaisher-Kinkelin constant A074962.
a(n) = 3*n*a(n-1)*Product_{i=1..n-1} (2*i+n)(2*n+i). - Chai Wah Wu, Feb 26 2019
a(n) = a(n-1) * (3*n)! * (3*n-2)!!/((2*n)! * n!!). - Robert Israel, Feb 27 2019

Extensions

a(0)=1 prepended by Alois P. Heinz, Jun 24 2023

A227143 Hankel determinants of order n of A225439(n): a(n)=det[A225439(i+j-2)], i,j=0..n, n>=0.

Original entry on oeis.org

1, 1, 12, 567, 122472, 126660105, 640190834712, 15987980408180508, 1985745116187976972608, 1231754497376142871049675940, 3826847477714307687323719819461000, 59670909707615018862830973519922857945375
Offset: 0

Views

Author

Karol A. Penson, Jul 02 2013

Keywords

Crossrefs

Programs

  • Maple
    with(LinearAlgebra):
    A225439 := proc(n) add(binomial(k,n-k)*3^(k)*(-1)^(n-k)*binomial(n+k-1,n-1), k=0..n) end:
    hank0:= (i, j)-> A225439(i+j-2):
    a:= proc(n) Determinant(Matrix(n,n,hank0)) end:
    seq(a(n), n=0..10);
  • Mathematica
    A225439[n_] := Sum[Binomial[k, n-k]*3^k*(-1)^(n-k)*Binomial[n+k-1, n-1], {k, 0, n}]; a[n_] := Det[Table[A225439[i+j-2], {i, n}, {j, n}]]; a[0] = 1; Table[ a[n], {n, 0, 11}] (* Jean-François Alcover, Nov 07 2016 *)

Formula

a(n) ~ c * (9/4)^(n^2) * n^(31/36) / 3^(n/2), where c = 2^(5/12) * exp(1/36) * Pi^(1/3) / (A^(1/3) * 3^(7/36) * Gamma(1/3)^(2/3)) = 0.774669663248120327054918681212809967565811826042305406436705141... and A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Feb 24 2019

A227379 Hankel determinants of order n of A225439(n): a(n) = det[A225439(i+j-1)], i,j=0..n, n>=0.

Original entry on oeis.org

1, 3, 45, 3402, 1299078, 2507870079, 24487299427734, 1209640056157393380, 302358334494179897593596, 382459771435292361460924379370, 2448391839613471201062299337071282925
Offset: 0

Views

Author

Karol A. Penson, Jul 09 2013

Keywords

Crossrefs

Programs

  • Maple
    with(LinearAlgebra):
    A225439 := proc(n) add(binomial(k, n-k)*3^(k)*(-1)^(n-k)*binomial(n+k-1, n-1), k=0..n) end:
    hank1:= (i, j)-> A225439(i+j-1):
    a:= proc(n) Determinant(Matrix(n, n, hank1)) end:
    seq(a(n), n=0..10);
  • Mathematica
    A225439[n_] := Sum[Binomial[k, n-k]*3^k*(-1)^(n-k)*Binomial[n+k-1, n-1], {k, 0, n}]; a[n_] := Det[Table[A225439[i+j-1], {i, n}, {j, n}]]; a[0] = 1; Table[ a[n], {n, 0, 11}] (* Vaclav Kotesovec, Feb 24 2019, after Jean-François Alcover *)

Formula

a(n) ~ c * 3^(n*(4*n + 3)/2) * n^(1/36) / 4^(n*(n+1)), where c = 3^(11/36) * exp(1/36) * Gamma(1/3)^(1/3) / (2^(7/12) * A^(1/3) * Pi^(1/6)) = 1.0139930857022957587164044116685749094666597031981229532... and A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Feb 24 2019
Showing 1-3 of 3 results.