a(n) = n*a(n-1) - n + 2 for n > 1; a(1)=1.

Terms

a(0) =1a(1) =2a(2) =5a(3) =18a(4) =87a(5) =518a(6) =3621a(7) =28962a(8) =260651a(9) =2606502a(10) =28671513a(11) =344058146a(12) =4472755887a(13) =62618582406a(14) =939278736077