G.f.: Product_{m>0} 1/(1 + x^m + 2!*x^(2*m)).

Terms

a(0) =1a(1) =-1a(2) =-2a(3) =3a(4) =-1a(5) =-5a(6) =9a(7) =3a(8) =-20a(9) =16a(10) =20a(11) =-54a(12) =19a(13) =89a(14) =-123a(15) =-56a(16) =287a(17) =-181a(18) =-383a(19) =748a(20) =37a(21) =-1520a(22) =1406a(23) =1619a(24) =-4439a(25) =1190a(26) =7768a(27) =-10102a(28) =-5494a(29) =25673