G.f. A(x) satisfies: 1 - x = Sum_{n>=0} (x^(2*n) + (-1)^n*A(x))^n.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =10a(5) =21a(6) =45a(7) =100a(8) =225a(9) =515a(10) =1190a(11) =2780a(12) =6550a(13) =15555a(14) =37187a(15) =89428a(16) =216163a(17) =524890a(18) =1279727a(19) =3131526a(20) =7688383a(21) =18933352a(22) =46754406a(23) =115750501a(24) =287238398a(25) =714340089a(26) =1780091533a(27) =4444198347a(28) =11114847215a(29) =27843451884