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

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =4a(5) =5a(6) =6a(7) =7a(8) =8a(9) =9a(10) =10a(11) =11a(12) =12a(13) =13a(14) =18a(15) =24a(16) =34a(17) =36a(18) =44a(19) =58a(20) =66a(21) =77a(22) =100a(23) =101a(24) =105a(25) =109a(26) =114a(27) =132a(28) =141a(29) =363