Expansion of (1+x)/(1-2x-x^2-x^3).

Terms

a(0) =1a(1) =3a(2) =7a(3) =18a(4) =46a(5) =117a(6) =298a(7) =759a(8) =1933a(9) =4923a(10) =12538a(11) =31932a(12) =81325a(13) =207120a(14) =527497a(15) =1343439a(16) =3421495a(17) =8713926a(18) =22192786a(19) =56520993a(20) =143948698a(21) =366611175a(22) =933692041a(23) =2377943955a(24) =6056191126a(25) =15424018248a(26) =39282171577a(27) =100044552528a(28) =254795294881a(29) =648917313867