[ exp(11/12)*n! ].

Terms

a(0) =2a(1) =5a(2) =15a(3) =60a(4) =300a(5) =1800a(6) =12604a(7) =100837a(8) =907541a(9) =9075411a(10) =99829522a(11) =1197954268a(12) =15573405484a(13) =218027676784