G.f. satisfies A(x) = 1 + x^4*A(x)^2 / (1 - x*A(x)).

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =1a(5) =1a(6) =1a(7) =1a(8) =3a(9) =6a(10) =10a(11) =15a(12) =26a(13) =49a(14) =92a(15) =165a(16) =294a(17) =535a(18) =994a(19) =1852a(20) =3437a(21) =6379a(22) =11905a(23) =22344a(24) =42058a(25) =79260a(26) =149601a(27) =283038a(28) =536806a(29) =1020066