23 times triangular numbers.

Terms

a(0) =0a(1) =23a(2) =69a(3) =138a(4) =230a(5) =345a(6) =483a(7) =644a(8) =828a(9) =1035a(10) =1265a(11) =1518a(12) =1794a(13) =2093a(14) =2415a(15) =2760a(16) =3128a(17) =3519a(18) =3933a(19) =4370a(20) =4830a(21) =5313a(22) =5819a(23) =6348a(24) =6900a(25) =7475a(26) =8073a(27) =8694a(28) =9338a(29) =10005