Triangular numbers with internal digits also forming a triangular number.

Terms

a(0) =105a(1) =136a(2) =210a(3) =231a(4) =300a(5) =406a(6) =435a(7) =465a(8) =561a(9) =630a(10) =666a(11) =703a(12) =861a(13) =903a(14) =1035a(15) =2016a(16) =2211a(17) =2556a(18) =3003a(19) =3916a(20) =4005a(21) =5151a(22) =6105a(23) =6216a(24) =6555a(25) =6786a(26) =8001a(27) =8911a(28) =9453a(29) =10011