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Numbers k such that k^2 contains only digits {0,1,9}, not ending with zero.
4

%I #14 Aug 11 2024 14:41:33

%S 1,3,43694278824566964251,100990098979999970099500001

%N Numbers k such that k^2 contains only digits {0,1,9}, not ending with zero.

%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#019">Sporadic tridigital solutions</a>

%H Zhao Hui Du, <a href="https://bbs.emath.ac.cn/forum.php?mod=redirect&amp;goto=findpost&amp;ptid=19296&amp;pid=99358">Chinese BBS with updated data</a>

%Y Cf. A058474.

%K nonn,base,hard,more

%O 1,2

%A _Patrick De Geest_, Nov 15 2000

%E a(4) from _Zhao Hui Du_, Feb 28 2024