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.

Previous Showing 11-13 of 13 results.

A138176 Hankel transform of A138175.

Original entry on oeis.org

1, -4, 144, -43264, 106832896, -2155963622400, 354617391605760000, -474686810341051524710400, 5166329306435680284163452174336, -456900249341808231214942590547243565056
Offset: 0

Views

Author

Paul Barry, Mar 03 2008

Keywords

Comments

When aerated, gives Hankel transform of A138175.

Formula

sqrt(abs(a(n)))/2^n = A005156(n).
a(n) = (-1)^n*(Product_{k=1..n} (6*k-2)!*(2*k-1)!/((4*k-1)!*(4*k-2)!))^2.

A173312 Partial sums of A005130.

Original entry on oeis.org

1, 2, 4, 11, 53, 482, 7918, 226266, 11076482, 922911942, 130457184642, 31226202037017, 12642538061714517, 8652026056359367017, 10004193381504526849017, 19539080428042781631746217
Offset: 0

Views

Author

Jonathan Vos Post, Feb 16 2010

Keywords

Comments

Partial sums of Robbins numbers. Partial sums of the number of descending plane partitions whose parts do not exceed n. Partial sums of the number of n X n alternating sign matrices (ASM's). After 2, 11, 53, when is this partial sum again prime, as it is not again prime through a(32)?

Examples

			a(17) = 1 + 1 + 2 + 7 + 42 + 429 + 7436 + 218348 + 10850216 + 911835460 + 129534272700 + 31095744852375 + 12611311859677500 + 8639383518297652500 + 9995541355448167482000 + 19529076234661277104897200 + 64427185703425689356896743840 + 358869201916137601447486156417296.
		

Crossrefs

Programs

  • Mathematica
    Table[Sum[Product[(3 k + 1)!/(j + k)!, {k, 0, j - 1}], {j, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Oct 26 2017 *)
    Accumulate[Table[Product[(3k+1)!/(n+k)!,{k,0,n-1}],{n,0,20}]] (* Harvey P. Dale, Feb 06 2019 *)

Formula

a(n) = Sum_{i=0..n} A005130(i) = Sum_{i=0..n} Product_{k=0..i-1} (3k+1)!/(i+k)!. [corrected by Vaclav Kotesovec, Oct 26 2017]
a(n) ~ Pi^(1/3) * exp(1/36) * 3^(3*n^2/2 - 7/36) / (A^(1/3) * Gamma(1/3)^(2/3) * n^(5/36) * 2^(2*n^2 - 5/12)), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Oct 26 2017

A156106 Expansion of F(1/3,2/3;1/2;27*x/2) / F(1/3,-1/3;-1/2;27*x/2).

Original entry on oeis.org

1, 3, 15, 99, 783, 6987, 67671, 694035, 7418943, 81800091, 923720679, 10630297827, 124224709455, 1470172954347, 17585028636279, 212248303720371, 2581823992868703
Offset: 0

Views

Author

Paul Barry, Feb 04 2009

Keywords

Comments

Hankel transform is 3^n*2^(n^2)*A005156 = 6^n*4^C(n,2)*A005156 = 3^n*A002416*A005156.

Formula

D-finite with recurrence: 2*(2*n-1)*(n-2)*a(n) + (-72*(n-3)^2-171*n+420)*a(n-1) + (297*(n-3)^2+675*n-1674)*a(n-2) - 81*(3*n-5)*(3*n-7)*a(n-3) = 0. - Georg Fischer, Nov 30 2022
Previous Showing 11-13 of 13 results.