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

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =17a(5) =36a(6) =76a(7) =162a(8) =345a(9) =734a(10) =1564a(11) =3332a(12) =7097a(13) =15121a(14) =32216a(15) =68634a(16) =146228a(17) =311544a(18) =663748a(19) =1414136a(20) =3012859a(21) =6418971a(22) =13675802a(23) =29136686a(24) =62076510a(25) =132255753a(26) =281774605a(27) =600328670a(28) =1279017082a(29) =2724981797