Numbers k such that the k-th triangular number contains only digits {1,4,6}.

Terms

a(0) =1a(1) =3a(2) =11a(3) =36a(4) =113a(5) =288a(6) =541a(7) =963a(8) =1711a(9) =2868a(10) =5313a(11) =36458a(12) =48258a(13) =182463a(14) =288588a(15) =363633a(16) =536956a(17) =568588a(18) =1711411a(19) =2988113a(20) =9425088a(21) =11055868a(22) =30533313a(23) =47257686a(24) =48200963a(25) =963446588a(26) =1527359886a(27) =1825604911a(28) =363633363333