a(n) = 6*(n - 3)*(n - 4)*2^(n-3)*n^(n-4).

A232994

a(n) = 6*(n - 3)*(n - 4)*2^(n-3)*n^(n-4).

Terms

    a(0) =0a(1) =0a(2) =240a(3) =10368a(4) =395136a(5) =15728640a(6) =680244480a(7) =32256000000

External references