OFFSET
0,2
FORMULA
a(n) ~ 2*3^(n+1/2) * n^(2*n+1) * sinh(Pi/sqrt(3)) / exp(2*n).
MATHEMATICA
Table[Product[3*k^2+1, {k, 1, n}], {n, 0, 15}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Oct 10 2016
STATUS
approved