Expansion of (1/(1-x+x^2))c(x/(1-x+x^2)), c(x) the g.f. of A000108.

Terms

a(0) =1a(1) =2a(2) =4a(3) =11a(4) =37a(5) =134a(6) =505a(7) =1964a(8) =7834a(9) =31880a(10) =131833a(11) =552392a(12) =2340181a(13) =10007048a(14) =43136554a(15) =187244489a(16) =817754563a(17) =3590696546a(18) =15842313289a(19) =70198094315a(20) =312258202582