Truncated square pyramid numbers: a(n) = Sum_{k = n..2*n-1} k^2.

Terms

a(0) =0a(1) =1a(2) =13a(3) =50a(4) =126a(5) =255a(6) =451a(7) =728a(8) =1100a(9) =1581a(10) =2185a(11) =2926a(12) =3818a(13) =4875a(14) =6111a(15) =7540a(16) =9176a(17) =11033a(18) =13125a(19) =15466a(20) =18070a(21) =20951a(22) =24123a(23) =27600a(24) =31396a(25) =35525a(26) =40001a(27) =44838a(28) =50050a(29) =55651