a(n) = n! * Sum_{d|n} 1/((d-1)! * (n/d)^d).

Terms

a(0) =1a(1) =3a(2) =5a(3) =16a(4) =29a(5) =251a(6) =727a(7) =7988a(8) =47049a(9) =512767a(10) =3628811a(11) =58012582a(12) =479001613a(13) =8007115559a(14) =92633212687