G.f. satisfies A(x) = x/(1-x) + Sum_{n>=1} A(x^n)^3.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =27a(6) =73a(7) =217a(8) =637a(9) =1960a(10) =6037a(11) =19051a(12) =60430a(13) =194245a(14) =628395a(15) =2049442a(16) =6722659a(17) =22179293a(18) =73523029a(19) =244807537a(20) =818317704a(21) =2745173455a(22) =9238878208a(23) =31185424166a(24) =105550046650a(25) =358134532723