G.f. 1-(2*x^3)/(-sqrt(-3*x^4-4*x^3-2*x^2+1)-x^2+1).

Terms

a(0) =1a(1) =0a(2) =1a(3) =0a(4) =1a(5) =1a(6) =2a(7) =3a(8) =6a(9) =10a(10) =19a(11) =35a(12) =66a(13) =125a(14) =240a(15) =462a(16) =897a(17) =1750a(18) =3431a(19) =6756a(20) =13357a(21) =26499a(22) =52744a(23) =105292a(24) =210761a(25) =422928a(26) =850631a(27) =1714505a(28) =3462538a(29) =7005661