Triangular numbers composed of digits {1,5,9}.

Terms

a(0) =1a(1) =15a(2) =55a(3) =91a(4) =595a(5) =5151a(6) =5995a(7) =9591a(8) =1511191a(9) =51151555a(10) =195911115a(11) =511151999595a(12) =519191199555a(13) =555595555515a(14) =595151955555