a(n) = floor(2*binomial(n+1,2)!/(binomial(n,2)!*n*(n^2+1))).

A075351

a(n) = floor(2*binomial(n+1,2)!/(binomial(n,2)!*n*(n^2+1))).

Terms

    a(0) =1a(1) =1a(2) =8a(3) =148a(4) =5544a(5) =351982a(6) =34100352a(7) =4692680418a(8) =871465795200

External references