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%I #14 Mar 27 2023 07:28:09
%S 70007020020,27272070272700,20720272227227700077007700020,
%T 22200020770272007007202277772702722200
%N Triangular numbers composed of digits {0,2,7}.
%C a(5) > 10^40.
%H Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr027.html">Tridigital Triangular Numbers</a>.
%F a(n) = A000217(A218398(n)).
%Y Cf. A000217, A218398. See A119033 for a table of cross-references.
%K base,nonn,more
%O 1,1
%A _Max Alekseyev_, Oct 28 2012
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