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.

A380296 Number of transfer systems for the Dihedral group of order 2p^n, with p an odd prime.

Original entry on oeis.org

2, 9, 56, 416, 3457, 31063, 295834, 2948082, 30471080, 324580196, 3546142551, 39588702271, 450277384320, 5205233568669, 61037153047708, 724817556942798, 8704492269996637, 105591602247646356, 1292561576650363350, 15952703801125660022, 198359915092340815084
Offset: 0

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Author

Ben Spitz, Jan 22 2025

Keywords

Comments

Balchin-MacBrough-Ormsby give a complicated recurrence relation for this sequence, but do not produce a closed form.

Formula

a(n) = sum of L(n,k,l,a,b) ranging over 1 <= k,l <= n+1, 0 <= a <= 1, 0 <= b <= n, where
L(n,k,l,0,0) = sum of L(n-1,k',l-1,a,b) ranging over k-1 <= k' <= n, 0 <= a <= 1, 0 <= b <= n-1
L(n,k,l,1,n) = sum of L(n-1,k-1,l',a,b) ranging over l-1 <= l' <= n, 0 <= a <= 1, 0 <= b <= n-1
For b>0, L(n,k,l,0,b) = sum of T(b-1,i)*L(n-b,k-i,l,0,0) ranging over 0 <= i <= k
For b
Otherwise, L(n,k,l,a,b) = 0,
where in the above T(x,y) = (2(2y + 1)!(4x - 2y + 3)!)/((y - 1)!(y + 1)!(x - y + 1)!(3x - y + 4)!).