a(n) = (n - 3)^2*(n - 4)*2^n*n^(n-5).

A232995

a(n) = (n - 3)^2*(n - 4)*2^n*n^(n-5).

Terms

    a(0) =0a(1) =0a(2) =128a(3) =6912a(4) =301056a(5) =13107200a(6) =604661760a(7) =30105600000

External references