a(n) = floor( Gamma(n+7/8)/Gamma(7/8) ).

Terms

a(0) =1a(1) =0a(2) =1a(3) =4a(4) =18a(5) =89a(6) =523a(7) =3598a(8) =28341a(9) =251531a(10) =2483877a(11) =27012163a(12) =320769440a(13) =4129906548a(14) =57302453360a(15) =852373993744