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Numbers k such that the k-th triangular number contains only digits {0,5,8}.
2

%I #8 Jul 13 2021 01:25:36

%S 10,100,1000,10000,100000,1000000,1056485,10000000,40212075,100000000,

%T 1000000000,10000000000,100000000000,100549051600,1000000000000,

%U 10000000000000,100000000000000,421438146839024,1000000000000000

%N Numbers k such that the k-th triangular number contains only digits {0,5,8}.

%H G. Resta, <a href="http://www.numbersaplenty.com/tr/tr058.html">Tridigital Triangular Numbers</a>

%Y Cf. A000217, A119083. See A119034 for a table of cross-references.

%K nonn,base

%O 1,1

%A _Giovanni Resta_, May 10 2006