a(n) = n*(n+1)*(5*n^2 - n - 3)/2.

Terms

a(0) =0a(1) =1a(2) =45a(3) =234a(4) =730a(5) =1755a(6) =3591a(7) =6580a(8) =11124a(9) =17685a(10) =26785a(11) =39006a(12) =54990a(13) =75439a(14) =101115a(15) =132840a(16) =171496a(17) =218025a(18) =273429a(19) =338770a(20) =415170a(21) =503811a(22) =605935a(23) =722844a(24) =855900a(25) =1006525a(26) =1176201a(27) =1366470a(28) =1578934a(29) =1815255