[ exp(3/19)*n! ].

Terms

a(0) =1a(1) =2a(2) =7a(3) =28a(4) =140a(5) =843a(6) =5902a(7) =47216a(8) =424948a(9) =4249480a(10) =46744286a(11) =560931432a(12) =7292108623a(13) =102089520734