A119131 - OEIS

%I #12 Jul 13 2021 07:28:22

%S 1,13,313,538,13741,43386,48886,991886,141415133,2880781113,

%T 4721227413,19567549258,538423521386,137473211871979931561

%N Numbers k such that the k-th triangular number contains only digits {1,4,9}.

%H G. Resta, <a href="http://www.numbersaplenty.com/tr/tr149.html">Tridigital Triangular Numbers</a>

%Y Cf. A000217, A119130. See A119034 for a table of cross-references.

%K nonn,base,more

%O 1,2

%A _Giovanni Resta_, May 10 2006

%E a(14) from _Max Alekseyev_, Aug 15 2013