a(n) = 14*n^3 - 30*n^2 + 24*n - 7.

Terms

a(0) =1a(1) =33a(2) =173a(3) =505a(4) =1113a(5) =2081a(6) =3493a(7) =5433a(8) =7985a(9) =11233a(10) =15261a(11) =20153a(12) =25993a(13) =32865a(14) =40853a(15) =50041a(16) =60513a(17) =72353a(18) =85645a(19) =100473a(20) =116921a(21) =135073a(22) =155013a(23) =176825a(24) =200593a(25) =226401a(26) =254333a(27) =284473a(28) =316905a(29) =351713