Expansion of (1/(1+4x+2x^2))*c(x/(1+4x+2x^2)), c(x) the g.f. of A000108.

Terms

a(0) =1a(1) =-3a(2) =8a(3) =-23a(4) =70a(5) =-218a(6) =688a(7) =-2195a(8) =7062a(9) =-22866a(10) =74416a(11) =-243206a(12) =797660a(13) =-2624004a(14) =8654304a(15) =-28607171a(16) =94748774a(17) =-314361682a(18) =1044625200a(19) =-3476135186a(20) =11581870900a(21) =-38632753228a(22) =128998096032a(23) =-431144781486