OFFSET
0,1
FORMULA
a(n) ~ c * d^n * 2^(4*n^3/3 + 3*n^2) * exp(n^2/4 + n) / (Pi^(n^2/2) * n^(n^2/2 + n + alfa), where
d = 1.7552437670085151253596298317411616254914764275962173772854884197280838467...
alfa = 0.0720289309157636194865104906223497131817905230497828189113545663815669...
c = 1.3392511999007422713775779654793976642559410116533455108049762435308676715...
MATHEMATICA
Table[Product[Binomial[2*i, i] + Binomial[2*j, j], {i, 0, n}, {j, 0, n}], {n, 0, 7}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Mar 07 2019
STATUS
approved