a(n) = Sum_{k=1..n} k^2 * (k+1)!.

Terms

a(0) =0a(1) =2a(2) =26a(3) =242a(4) =2162a(5) =20162a(6) =201602a(7) =2177282a(8) =25401602a(9) =319334402a(10) =4311014402a(11) =62270208002a(12) =958961203202