7 times octagonal numbers: a(n) = 7*n*(3*n-2).

Terms

a(0) =0a(1) =7a(2) =56a(3) =147a(4) =280a(5) =455a(6) =672a(7) =931a(8) =1232a(9) =1575a(10) =1960a(11) =2387a(12) =2856a(13) =3367a(14) =3920a(15) =4515a(16) =5152a(17) =5831a(18) =6552a(19) =7315a(20) =8120a(21) =8967a(22) =9856a(23) =10787a(24) =11760a(25) =12775a(26) =13832a(27) =14931a(28) =16072a(29) =17255