Numbers k such that the triangular number k*(k+1)/2 has 2 different digits in base 10.

Terms

a(0) =4a(1) =5a(2) =6a(3) =7a(4) =8a(5) =9a(6) =12a(7) =13a(8) =18a(9) =24a(10) =34a(11) =44a(12) =58a(13) =66a(14) =77a(15) =100a(16) =101a(17) =105a(18) =109a(19) =114a(20) =132a(21) =141a(22) =363a(23) =666a(24) =714a(25) =816a(26) =1000a(27) =1095a(28) =1287a(29) =1332