OFFSET
0,2
LINKS
Robert Israel, Table of n, a(n) for n = 0..25
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
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}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Feb 26 2019
EXTENSIONS
a(0)=1 prepended by Alois P. Heinz, Jun 24 2023
STATUS
approved