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%I #7 Oct 26 2019 17:57:51
%S 9,98989978877879888789778997998889
%N Squares composed of digits {7,8,9}.
%H P. De Geest, <a href="http://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>
%F a(n) = A058471(n)^2.
%Y Cf. A058471.
%K nonn,base,hard,more,bref
%O 1,1
%A _Patrick De Geest_, Nov 15 2000
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