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

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =5a(5) =11a(6) =23a(7) =51a(8) =120a(9) =286a(10) =681a(11) =1636a(12) =3985a(13) =9803a(14) =24257a(15) =60338a(16) =150931a(17) =379501a(18) =958360a(19) =2429294a(20) =6179380a(21) =15769380a(22) =40361087a(23) =103579221a(24) =266471500a(25) =687098810a(26) =1775440421a(27) =4596689688a(28) =11922774513a(29) =30977768907