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%I #8 Jul 13 2021 01:24:24
%S 12,39,132,1332,13332,41732,118387,126560,133332,1241612,1333332,
%T 11905535,13333332,124970227,133333332,1333333332,11906972812,
%U 13333333332,37418660507,37626774267,42163256012,133333333332
%N Numbers k such that the k-th triangular number contains only digits {0,7,8}.
%H G. Resta, <a href="http://www.numbersaplenty.com/tr/tr078.html">Tridigital Triangular Numbers</a>
%Y Cf. A000217, A119093. See A119034 for a table of cross-references.
%K nonn,base
%O 1,1
%A _Giovanni Resta_, May 10 2006