a(n) = Sum_{k=0..n} (-1)^(n-k)*Bell(k).

Terms

a(0) =1a(1) =0a(2) =2a(3) =3a(4) =12a(5) =40a(6) =163a(7) =714a(8) =3426a(9) =17721a(10) =98254a(11) =580316a(12) =3633281a(13) =24011156a(14) =166888166a(15) =1216070379a(16) =9264071768a(17) =73600798036a(18) =608476008123