Triangular numbers with property that swapping first and last digits also gives a triangular number.

A069708

Triangular numbers with property that swapping first and last digits also gives a triangular number.

Terms

    a(0) =1a(1) =3a(2) =6a(3) =10a(4) =55a(5) =66a(6) =120a(7) =153a(8) =171a(9) =190a(10) =300a(11) =351a(12) =595a(13) =630a(14) =666a(15) =820a(16) =1081a(17) =1431a(18) =1711a(19) =1891a(20) =3003a(21) =3403a(22) =5050a(23) =5460a(24) =5565a(25) =5995a(26) =6216a(27) =6786a(28) =8128a(29) =8778

External references