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%I #7 Aug 11 2024 14:41:33
%S 3,9949370777987917
%N Numbers k such that k^2 contains only digits {7,8,9}.
%H P. De Geest, <a href="https://www.worldofnumbers.com/threedigits.htm">Index to related sequences</a>
%H Hisanori Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/math02/math0210.htm#789">Sporadic tridigital solutions</a>
%Y Cf. A058472.
%K nonn,base,hard,more,bref
%O 1,1
%A _Patrick De Geest_, Nov 15 2000