G.f. satisfies A(x) = 1 + 2*x*A(x) + 2*x^4*A(x)^4.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =18a(5) =52a(6) =184a(7) =688a(8) =2512a(9) =8864a(10) =30784a(11) =107648a(12) =384432a(13) =1403872a(14) =5205568a(15) =19443328a(16) =72817856a(17) =273199488a(18) =1027939072a(19) =3883718144a(20) =14741042464a(21) =56189409088a(22) =214931447680a(23) =824443822848