A144545 a(n) = 2^(n*(n-1))*(2^n + 1)*Product_{i=1..n-1} (4^i - 1).

2, 3, 60, 25920, 197406720, 25015379558400, 51615733565620224000, 1718194449153210615595008000, 918817155086936330770931156779008000, 7877103854727828347931810809383874168094720000, 1081561598265935342583934931877242782978883444539392000000

Offset: 0

Author

N. J. A. Sloane, Dec 30 2008

Keywords

• nonn

Links

• T. D. Noe, Table of n, a(n) for n = 0..20

Crossrefs

Cf. A003923, A001308, A003053, A100221.

Programs

Maple

g:=m->2^(m*(m-1))*mul( 4^i-1, i=1..m-1)*(2^m+1);

Mathematica

a[n_] := 2^(n*(n-1))*(2^n + 1) * Product[4^i - 1, {i, 1, n-1}]; Array[a, 10, 0] (* Amiram Eldar, Jul 07 2025 *)

Python

from math import prod
def A144545(n): return ((1<Chai Wah Wu, Jun 20 2022

Formula

a(n) ~ c * 2^(2*n^2-n), where c = A100221. - Amiram Eldar, Jul 07 2025