a(n) = (35*n^4 - 105*n^3 + 160*n^2 - 120*n + 36)/6.

Terms

a(0) =1a(1) =26a(2) =186a(3) =726a(4) =2031a(5) =4626a(6) =9176a(7) =16486a(8) =27501a(9) =43306a(10) =65126a(11) =94326a(12) =132411a(13) =181026a(14) =241956a(15) =317126a(16) =408601a(17) =518586a(18) =649426a(19) =803606a(20) =983751a(21) =1192626a(22) =1433136a(23) =1708326a(24) =2021381a(25) =2375626a(26) =2774526a(27) =3221686a(28) =3720851a(29) =4275906