a(n) = n*a(n-1) + n^(n mod 2), a(0) = 0.

Terms

a(0) =0a(1) =1a(2) =3a(3) =12a(4) =49a(5) =250a(6) =1501a(7) =10514a(8) =84113a(9) =757026a(10) =7570261a(11) =83272882a(12) =999274585a(13) =12990569618a(14) =181867974653