OFFSET
0,2
FORMULA
a(n) ~ A^(1/3) * 2^(16*n*(n+1)/3 + 13/18) * n^(n^2 - 19/36) / (Pi^(1/3) * Gamma(1/3)^(1/3) * 3^(n*(3*n+4)/2 + 11/36) * exp(3*n^2/2 + 1/36)), where A = A074962 is the Glaisher-Kinkelin constant.
MATHEMATICA
Table[Product[i + 3*j, {i, 1, n}, {j, 1, n}], {n, 0, 10}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Dec 06 2023
STATUS
approved