G.f.: x*(1+x+x^2)*(1+6*x+8*x^2+4*x^3-x^4)/((1+x)^2*(1-x)^4).

Terms

a(0) =0a(1) =1a(2) =9a(3) =34a(4) =91a(5) =192a(6) =353a(7) =584a(8) =903a(9) =1318a(10) =1849a(11) =2502a(12) =3299a(13) =4244a(14) =5361a(15) =6652a(16) =8143a(17) =9834a(18) =11753a(19) =13898a(20) =16299a(21) =18952a(22) =21889a(23) =25104a(24) =28631a(25) =32462a(26) =36633a(27) =41134a(28) =46003a(29) =51228