A371645 a(n) = Product_{k=0..n} (2*k^2)!.

1, 2, 80640, 516287415629905920000, 135851139773030831011345707357554182190215987200000000000

Offset: 0

Author

Vaclav Kotesovec, Mar 31 2024

Keywords

• nonn

Comments

The next term has 121 digits.

Crossrefs

Cf. A255322.

Programs

Mathematica

Table[Product[(2*k^2)!, {k, 0, n}], {n, 0, 6}]

Formula

a(n) ~ c * 2^(2*n^3/3 + n^2 + 4*n/3) * Pi^(n/2) * n^(4*n^3/3 + 2*n^2 + 5*n/3 + 1/2) / exp(10*n^3/9 + n^2 + n), where c = 3.03114159524498232897099596239043047625469924617878376047699145874714076...