G.f. A(x) = Sum_{n=-oo..+oo} x^n * (1 + x^n)^(2*n).

Terms

a(0) =1a(1) =2a(2) =1a(3) =5a(4) =1a(5) =6a(6) =8a(7) =8a(8) =1a(9) =25a(10) =12a(11) =12a(12) =29a(13) =14a(14) =36a(15) =77a(16) =1a(17) =18a(18) =151a(19) =20a(20) =71a(21) =135a(22) =166a(23) =24a(24) =121a(25) =236a(26) =287a(27) =307a(28) =30a(29) =30