a(n) = Sum_{k=0..n} binomial(n,k) * (-1)^(n-k) * (2^k + 1)^k.

A251183

a(n) = Sum_{k=0..n} binomial(n,k) * (-1)^(n-k) * (2^k + 1)^k.

Terms

    a(0) =1a(1) =2a(2) =20a(3) =662a(4) =80744a(5) =38724842a(6) =75185316860

External references