Numbers k such that the k-th triangular number contains only digits {1,5,6}.

Terms

a(0) =1a(1) =3a(2) =5a(3) =10a(4) =11a(5) =33a(6) =36a(7) =101a(8) =105a(9) =114a(10) =333a(11) =336a(12) =471a(13) =1011a(14) =1063a(15) =1141a(16) =1769a(17) =3333a(18) =3336a(19) =3363a(20) =3366a(21) =5588a(22) =5773a(23) =10114a(24) =10541a(25) =11096a(26) =11411a(27) =15241a(28) =33333a(29) =33336