[ exp(13/15)*n! ].

Terms

a(0) =2a(1) =4a(2) =14a(3) =57a(4) =285a(5) =1712a(6) =11989a(7) =95919a(8) =863279a(9) =8632798a(10) =94960779a(11) =1139529348a(12) =14813881536a(13) =207394341513