A071605(n)/(n-1)!.

Terms

a(0) =1a(1) =3a(2) =9a(3) =36a(4) =285a(5) =1908a(6) =21630a(7) =197328a(8) =2113911a(9) =23814810a(10) =294557142a(11) =3893052636a(12) =55457566905