a(n) = n*(n+1)*(7*n^2 - n - 4)/4.

Terms

a(0) =0a(1) =1a(2) =33a(3) =168a(4) =520a(5) =1245a(6) =2541a(7) =4648a(8) =7848a(9) =12465a(10) =18865a(11) =27456a(12) =38688a(13) =53053a(14) =71085a(15) =93360a(16) =120496a(17) =153153a(18) =192033a(19) =237880a(20) =291480a(21) =353661a(22) =425293a(23) =507288a(24) =600600a(25) =706225a(26) =825201a(27) =958608a(28) =1107568a(29) =1273245