a(1)=1, a(n) = -1 + n*Sum_{j=1..n-1} a(j).

Terms

a(0) =1a(1) =1a(2) =5a(3) =27a(4) =169a(5) =1217a(6) =9939a(7) =90871a(8) =920069a(9) =10222989a(10) =123698167a(11) =1619321459a(12) =22805443881a(13) =343835923129