A277353 a(n) = Product_{k=1..n} (3*k^2+1).

1, 4, 52, 1456, 71344, 5422144, 591013696, 87470027008, 16881715212544, 4119138511860736, 1239860692070081536, 451309291913509679104, 195416923398549691052032, 99271797086463243054432256, 58471088483926850159060598784, 39526455815134550707524964777984

Offset: 0

Author

Vaclav Kotesovec, Oct 10 2016

Keywords

• nonn

Crossrefs

Cf. A101686, A277352, A277354.

Programs

Mathematica

Table[Product[3*k^2+1, {k, 1, n}], {n, 0, 15}]

Formula

a(n) ~ 2*3^(n+1/2) * n^(2*n+1) * sinh(Pi/sqrt(3)) / exp(2*n).