a(n) = floor( exp(7/17)*n! ).

Terms

a(0) =1a(1) =3a(2) =9a(3) =36a(4) =181a(5) =1086a(6) =7607a(7) =60862a(8) =547759a(9) =5477598a(10) =60253580a(11) =723042962a(12) =9399558518a(13) =131593819259