G.f. A(x) satisfies A(x) = 1 / ((1 - x) * (1 - x * (1 + x + x^2 + x^3) * A(x^4))).

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =16a(5) =33a(6) =68a(7) =140a(8) =288a(9) =594a(10) =1225a(11) =2526a(12) =5208a(13) =10740a(14) =22148a(15) =45673a(16) =94184a(17) =194224a(18) =400524a(19) =825950a(20) =1703249a(21) =3512395a(22) =7243168a(23) =14936668a(24) =30801992a(25) =63519044a(26) =130987274a(27) =270118452a(28) =557031032a(29) =1148694482