G.f. A(x) satisfies: 1 - x = Sum_{n>=0} (x^(4*n) + (-1)^n*A(x))^n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =4a(6) =5a(7) =7a(8) =12a(9) =20a(10) =31a(11) =48a(12) =78a(13) =131a(14) =217a(15) =354a(16) =581a(17) =971a(18) =1634a(19) =2739a(20) =4580a(21) =7699a(22) =13027a(23) =22092a(24) =37449a(25) =63551a(26) =108176a(27) =184637a(28) =315530a(29) =539625