E.g.f.: Product_{k>=1} (1 + x^(4*k-3) / (4*k-3)).

Terms

a(0) =1a(1) =1a(2) =0a(3) =0a(4) =0a(5) =24a(6) =144a(7) =0a(8) =0a(9) =40320a(10) =403200a(11) =0a(12) =0a(13) =479001600a(14) =8643317760a(15) =29059430400a(16) =0a(20) =0a(24) =0