G.f.: Product_{n>=1} ((1-x^n)/(1+x^n))^(2*n).

Terms

a(0) =1a(1) =-4a(2) =0a(3) =8a(4) =16a(5) =-8a(6) =-48a(7) =-56a(8) =0a(9) =116a(10) =256a(11) =264a(12) =-32a(13) =-648a(14) =-1296a(15) =-1392a(16) =-352a(17) =2040a(18) =5200a(19) =7368a(20) =6112a(21) =-784a(22) =-13744a(23) =-29304a(24) =-39648a(25) =-33804a(26) =-1376a(27) =60368a(28) =139552a(29) =205304