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

Terms

a(0) =1a(1) =1a(2) =0a(3) =-1a(4) =-1a(5) =3a(6) =3a(7) =-1a(8) =-8a(9) =-8a(10) =12a(11) =24a(12) =5a(13) =-43a(14) =-55a(15) =40a(16) =137a(17) =65a(18) =-215a(19) =-356a(20) =97a(21) =780a(22) =624a(23) =-941a(24) =-2199a(25) =-260a(26) =4052a(27) =4638a(28) =-3536a(29) =-12861