Numbers n whose sum of divisors and number of divisors are both triangular numbers.

Terms

a(0) =1a(1) =12a(2) =45a(3) =98a(4) =116a(5) =212a(6) =356a(7) =531a(8) =668a(9) =908a(10) =909a(11) =2036a(12) =2192a(13) =3425a(14) =3548a(15) =3771a(16) =3871a(17) =4076a(18) =4500a(19) =4689a(20) =4779a(21) =5625a(22) =5636a(23) =6212a(24) =6224a(25) =8012a(26) =8108a(27) =8361a(28) =8469a(29) =8800