a(n) = 1 + 2*n + 3*n^2 + 4*n^3 + 5*n^4 + 6*n^5.

Terms

a(0) =1a(1) =21a(2) =321a(3) =2005a(4) =7737a(5) =22461a(6) =54121a(7) =114381a(8) =219345a(9) =390277a(10) =654321a(11) =1045221a(12) =1604041a(13) =2379885a(14) =3430617a(15) =4823581a(16) =6636321a(17) =8957301a(18) =11886625a(19) =15536757a(20) =20033241a(21) =25515421a(22) =32137161a(23) =40067565a(24) =49491697a(25) =60611301a(26) =73645521