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

Terms

a(0) =1a(1) =1a(2) =4a(3) =17a(4) =89a(5) =551a(6) =3946a(7) =32119a(8) =293017a(9) =2962289a(10) =32878196a(11) =397500641a(12) =5200386529a(13) =73202912047