OFFSET
0,3
LINKS
Eric Weisstein's World of Mathematics, Plane Partition
FORMULA
a(n) = [(x*y)^n] Product_{k>=1} 1 / ((1 - x^k) * (1 - y^k))^k.
a(n) = A000219(n)^2.
MATHEMATICA
nmax = 28; CoefficientList[Series[Product[1/(1 - x^k)^k, {k, 1, nmax}], {x, 0, nmax}], x]^2
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Apr 24 2025
STATUS
approved
