a(n) = n^3 - n - 1.

Terms

a(0) =-1a(1) =5a(2) =23a(3) =59a(4) =119a(5) =209a(6) =335a(7) =503a(8) =719a(9) =989a(10) =1319a(11) =1715a(12) =2183a(13) =2729a(14) =3359a(15) =4079a(16) =4895a(17) =5813a(18) =6839a(19) =7979a(20) =9239a(21) =10625a(22) =12143a(23) =13799a(24) =15599a(25) =17549a(26) =19655a(27) =21923a(28) =24359a(29) =26969