[ exp(3/4)*n! ].

Terms

a(0) =2a(1) =4a(2) =12a(3) =50a(4) =254a(5) =1524a(6) =10669a(7) =85357a(8) =768216a(9) =7682169a(10) =84503866a(11) =1014046395a(12) =13182603137a(13) =184556443918