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

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =11a(5) =26a(6) =64a(7) =159a(8) =402a(9) =1032a(10) =2677a(11) =7010a(12) =18510a(13) =49220a(14) =131691a(15) =354282a(16) =957745a(17) =2600382a(18) =7088008a(19) =19388719a(20) =53207441a(21) =146444424a(22) =404151643a(23) =1118132954a(24) =3100540971a(25) =8615945102a(26) =23989662824a(27) =66917894562a(28) =186983937758a(29) =523314016245