G.f. A(x) satisfies A(x) = 1 + x*(1-x^3)^2*A(x)^2.

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =12a(5) =34a(6) =102a(7) =318a(8) =1022a(9) =3353a(10) =11182a(11) =37788a(12) =129108a(13) =445235a(14) =1547710a(15) =5417478a(16) =19078334a(17) =67548056a(18) =240302580a(19) =858541455a(20) =3079197456a(21) =11082288288a(22) =40012944894a(23) =144887840770a(24) =526041042648