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

Terms

a(0) =1a(1) =1a(2) =4a(3) =6a(4) =17a(5) =31a(6) =76a(7) =152a(8) =349a(9) =729a(10) =1624a(11) =3462a(12) =7605a(13) =16367a(14) =35720a(15) =77216a(16) =168009a(17) =363937a(18) =790748a(19) =1714550a(20) =3722857a(21) =8075759a(22) =17529780a(23) =38034200a(24) =82547781a(25) =179120601a(26) =388729744a(27) =843543766a(28) =1830612397a(29) =3972513951