a(n) = n*(n+1)*(2*n+1).

Terms

a(0) =0a(1) =6a(2) =30a(3) =84a(4) =180a(5) =330a(6) =546a(7) =840a(8) =1224a(9) =1710a(10) =2310a(11) =3036a(12) =3900a(13) =4914a(14) =6090a(15) =7440a(16) =8976a(17) =10710a(18) =12654a(19) =14820a(20) =17220a(21) =19866a(22) =22770a(23) =25944a(24) =29400a(25) =33150a(26) =37206a(27) =41580a(28) =46284a(29) =51330