Numerator of Sum_{k=1..n} n^k/k!.

Terms

a(0) =1a(1) =4a(2) =12a(3) =100a(4) =1085a(5) =1218a(6) =47201a(7) =556088a(8) =10659753a(9) =7281020a(10) =62927202701a(11) =7217988a(13) =595952851172