Triangular numbers whose sum of aliquot divisors is also a triangular number.

Terms

a(0) =1a(1) =3a(2) =6a(3) =28a(4) =36a(5) =66a(6) =91a(7) =231a(8) =496a(9) =8128a(10) =14196a(11) =15225a(12) =129795a(13) =491536a(14) =780625a(15) =2476425a(16) =33550336a(17) =488265625a(18) =728302695a(19) =7403072040a(20) =8589869056a(21) =101548795116a(22) =134027094930a(23) =137438691328