%I #11 Mar 31 2023 03:20:41
%S 9,10,3390,38589,12453549,3080826336474,298253071929010,
%T 33089502135135685
%N Numbers k such that the k-th triangular number contains only digits {4,5,7}.
%H Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr457.html">Tridigital Triangular Numbers</a>.
%Y Cf. A000217, A119204. See A119034 for a table of cross-references.
%K nonn,base,more
%O 1,1
%A _Giovanni Resta_, May 10 2006
%E a(8) from _Tyler Busby_, Mar 31 2023
|