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

Terms

a(0) =1a(1) =0a(2) =0a(3) =2a(4) =0a(5) =0a(6) =0a(7) =720a(8) =0a(9) =0a(10) =172800a(11) =3628800a(12) =0a(13) =0a(14) =2641766400a(15) =87178291200a(16) =0a(17) =0a(20) =0a(24) =0