Expansion of (1+x*c(x^2))^3/sqrt(1-4*x^2), c(x) the g.f. of A000108.

Terms

a(0) =1a(1) =3a(2) =5a(3) =10a(4) =18a(5) =35a(6) =65a(7) =126a(8) =238a(9) =462a(10) =882a(11) =1716a(12) =3300a(13) =6435a(14) =12441a(15) =24310a(16) =47190a(17) =92378a(18) =179894a(19) =352716a(20) =688636a(21) =1352078a(22) =2645370a(23) =5200300a(24) =10192588a(25) =20058300a(26) =39373700a(27) =77558760a(28) =152443080a(29) =300540195