a(n) = (2^n/n!) * Product_{k=0..n-1} (4*k + 3).

A004982

a(n) = (2^n/n!) * Product_{k=0..n-1} (4*k + 3).

Terms

    a(0) =1a(1) =6a(2) =42a(3) =308a(4) =2310a(5) =17556a(6) =134596a(7) =1038312a(8) =8046918a(9) =62587140a(10) =488179692a(11) =3816677592a(12) =29897307804a(13) =234578876616

External references