a(n) = floor( exp(11/19)*n! ).

Terms

a(0) =1a(1) =3a(2) =10a(3) =42a(4) =214a(5) =1284a(6) =8992a(7) =71937a(8) =647435a(9) =6474357a(10) =71217933a(11) =854615197a(12) =11109997566a(13) =155539965928