T(n)^3 - n^3 where T(n) is a triangular number.

Terms

a(0) =0a(1) =19a(2) =189a(3) =936a(4) =3250a(5) =9045a(6) =21609a(7) =46144a(8) =90396a(9) =165375a(10) =286165a(11) =472824a(12) =751374a(13) =1154881a(14) =1724625a(15) =2511360a(16) =3576664a(17) =4994379a(18) =6852141a(19) =9253000a(20) =12317130a(21) =16183629a(22) =21012409a(23) =26986176a(24) =34312500a(25) =43225975a(26) =53990469a(27) =66901464a(28) =82288486a(29) =100517625