a(n) = n! * [x^n] exp(n*tan(x)).

Terms

a(0) =1a(1) =1a(2) =4a(3) =33a(4) =384a(5) =5705a(6) =103392a(7) =2213225a(8) =54648832a(9) =1529006769a(10) =47806489600