OFFSET
0,1
FORMULA
a(n) ~ c * d^n * exp(2*n^3/3 + 9*n^2/4) / (2^(n^2) * Pi^(n^2/2) * n^(n^2/2 + 5*n/6 - alfa)), where
d = 2.631186542501652610455988727776308850706336468478433795517960445788077147...
alfa = 0.094637735750903047180156176044316953484876143616883847755312100285099...
c = 0.121223472988717836553569221604723373713338356783096...
MATHEMATICA
Table[Product[Binomial[2*i, j] + Binomial[2*j, i], {i, 0, n}, {j, 0, n}], {n, 0, 7}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Mar 07 2019
STATUS
approved