[ exp(6/23)*n! ].

Terms

a(0) =1a(1) =2a(2) =7a(3) =31a(4) =155a(5) =934a(6) =6542a(7) =52337a(8) =471039a(9) =4710394a(10) =51814335a(11) =621772022a(12) =8083036297a(13) =113162508171