Coefficient of x^5 in (1-x-x^2)^(-n).

Terms

a(0) =8a(1) =38a(2) =111a(3) =256a(4) =511a(5) =924a(6) =1554a(7) =2472a(8) =3762a(9) =5522a(10) =7865a(11) =10920a(12) =14833a(13) =19768a(14) =25908a(15) =33456a(16) =42636a(17) =53694a(18) =66899a(19) =82544a(20) =100947a(21) =122452a(22) =147430a(23) =176280a(24) =209430a(25) =247338a(26) =290493a(27) =339416a(28) =394661a(29) =456816