OFFSET
0,2
FORMULA
a(n) ~ A * 2^(2*n*(n+1) + 1/4) * exp(Pi*(n*(n+1) + 1/6)/sqrt(3) - 9*n^2/2 - 1/12) * n^(3*n^2 - 3/4) / (3^(5/6) * Pi^(1/6) * Gamma(2/3)^2), where A is the Glaisher-Kinkelin constant A074962.
For n>0, a(n)/a(n-1) = A272246(n)^2 / (2*n^9). - Vaclav Kotesovec, Dec 02 2023
MAPLE
a:= n-> mul(mul(i^3+j^3, i=1..n), j=1..n):
seq(a(n), n=0..7); # Alois P. Heinz, Jun 24 2023
MATHEMATICA
Table[Product[i^3+j^3, {i, 1, n}, {j, 1, n}], {n, 1, 10}]
PROG
(PARI) a(n) = prod(i=1, n, prod(j=1, n, i^3+j^3)); \\ Michel Marcus, Feb 27 2019
(Python)
from math import prod, factorial
def A324426(n): return prod(i**3+j**3 for i in range(1, n) for j in range(i+1, n+1))**2*factorial(n)**3<<n # Chai Wah Wu, Nov 26 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Feb 27 2019
EXTENSIONS
a(0)=1 prepended by Alois P. Heinz, Jun 24 2023
STATUS
approved