a(n) = floor( Gamma(n+1/8)/Gamma(1/8) ).

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =0a(5) =3a(6) =19a(7) =120a(8) =861a(9) =7000a(10) =63875a(11) =646742a(12) =7195012a(13) =87239530a(14) =1145018831a(15) =16173391001a(16) =244622538902