%I #8 Jul 13 2021 01:25:25
%S 44,2831780,1407437419,140715344155
%N Numbers k such that the k-th triangular number contains only digits {0,4,9}.
%C Next term exceeds 1.4*10^16.
%H G. Resta, <a href="http://www.numbersaplenty.com/tr/tr049.html">Tridigital Triangular Numbers</a>
%Y Cf. A000217, A119077. See A119034 for a table of cross-references.
%K nonn,base,more
%O 1,1
%A _Giovanni Resta_, May 10 2006