[ exp(4/23)*n! ].

Terms

a(0) =1a(1) =2a(2) =7a(3) =28a(4) =142a(5) =856a(6) =5997a(7) =47978a(8) =431809a(9) =4318098a(10) =47499079a(11) =569988953a(12) =7409856398a(13) =103737989574