A346463 a(n) = 6 * GaussBinomial(2*n, 2, 2) / denominator(Bernoulli(2*n, 1)).

0, 1, 7, 93, 2159, 15841, 6141, 44731051, 8421119, 86113647, 3331843885, 127479517837, 103104368637, 750599904340651, 82824819807611, 80500035008073, 36170086393773823, 49191317521302203051, 2460603943675971, 12592977287514948283051, 89351501819019263845

Offset: 0

Author

Peter Luschny, Jul 19 2021

Keywords

• nonn

Crossrefs

Cf. A006095, A002445, A160014, A346464.

Programs

Maple

a := n -> (4^n - 2)*(4^n - 1) / mul(i, i=select(isprime, map(i->i+1, numtheory[divisors] (2*n)))): seq(a(n), n = 0..20);

Mathematica

Table[6 QBinomial[2 n, 2, 2] / Denominator[BernoulliB[2 n, 1]], {n, 0, 20}]

Formula

a(n) = (4^n - 2)*(4^n - 1)/Clausen(2*n, 1), where Clausen(n, k) = A160014(n, k).