a(n) = (2*n-1)*(5*n^2-5*n+2)/2.

Terms

a(0) =1a(1) =18a(2) =80a(3) =217a(4) =459a(5) =836a(6) =1378a(7) =2115a(8) =3077a(9) =4294a(10) =5796a(11) =7613a(12) =9775a(13) =12312a(14) =15254a(15) =18631a(16) =22473a(17) =26810a(18) =31672a(19) =37089a(20) =43091a(21) =49708a(22) =56970a(23) =64907a(24) =73549a(25) =82926a(26) =93068a(27) =104005a(28) =115767a(29) =128384