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

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =8a(5) =16a(6) =32a(7) =65a(8) =131a(9) =264a(10) =534a(11) =1078a(12) =2176a(13) =4396a(14) =8877a(15) =17925a(16) =36202a(17) =73108a(18) =147636a(19) =298152a(20) =602108a(21) =1215933a(22) =2455552a(23) =4958915a(24) =10014374a(25) =20223760a(26) =40841302a(27) =82477816a(28) =166561622a(29) =336366426