Nine times hexagonal numbers: a(n) = 9*n*(2*n-1).

Terms

a(0) =0a(1) =9a(2) =54a(3) =135a(4) =252a(5) =405a(6) =594a(7) =819a(8) =1080a(9) =1377a(10) =1710a(11) =2079a(12) =2484a(13) =2925a(14) =3402a(15) =3915a(16) =4464a(17) =5049a(18) =5670a(19) =6327a(20) =7020a(21) =7749a(22) =8514a(23) =9315a(24) =10152a(25) =11025a(26) =11934a(27) =12879a(28) =13860a(29) =14877