%I #9 Mar 22 2023 13:11:39
%S 1,6,66,171,666,1176,1711,17766,61776,67161,166176,617716,7767711,
%T 61677171,77171676,161667171,166777716,611677776,66767167176,
%U 77111161116,171676611666,617617761166,1116177116671,161776717667666676,1116166667661771771,6667177116611677771
%N Triangular numbers composed of digits {1,6,7}.
%H Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr167.html">Tridigital Triangular Numbers</a>
%F a(n) = A000217(A119141(n)). - _Michel Marcus_, Mar 22 2023
%Y Cf. A000217, A053907, A119141. See A119033 for a table of cross-references.
%K nonn,base
%O 1,2
%A _Giovanni Resta_, May 10 2006
%E a(24)-a(26) from _Tyler Busby_, Mar 22 2023
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