15-gonal (or pentadecagonal) pyramidal numbers: a(n) = n*(n+1)*(13*n-10)/6.

Terms

a(0) =0a(1) =1a(2) =16a(3) =58a(4) =140a(5) =275a(6) =476a(7) =756a(8) =1128a(9) =1605a(10) =2200a(11) =2926a(12) =3796a(13) =4823a(14) =6020a(15) =7400a(16) =8976a(17) =10761a(18) =12768a(19) =15010a(20) =17500a(21) =20251a(22) =23276a(23) =26588a(24) =30200a(25) =34125a(26) =38376a(27) =42966a(28) =47908a(29) =53215