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

Terms

a(0) =1a(1) =2a(2) =6a(3) =22a(4) =98a(5) =522a(6) =3262a(7) =23486a(8) =191802a(9) =1753618a(10) =17755382a(11) =197282022a(12) =2387112466a(13) =31249472282a(14) =440096734638