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Numbers k such that k and k^2 use only the digits 0, 1, 5, 7 and 9.
1

%I #7 Apr 12 2024 09:51:26

%S 0,1,10,100,1000,10000,100000,1000000,10000000,100000000,1000000000,

%T 9777075001,10000000000,97770750010,100000000000,717997055001,

%U 959050150501,977707500100,1000000000000,7179970550010,7550970170501,9590501505010,9777075001000,10000000000000,71799705500100,75509701705010

%N Numbers k such that k and k^2 use only the digits 0, 1, 5, 7 and 9.

%C Generated with DrScheme.

%H Jonathan Wellons, <a href="/A136873/b136873.txt">Table of n, a(n) for n = 1..37</a>

%H J. Wellons, <a href="https://web.archive.org/web/20090206165028/http://jonathanwellons.com/shared-digits/">Tables of Shared Digits</a> [archived]

%e 7550970170501^2 = 57017150515795901010591001.

%K base,nonn

%O 1,3

%A Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008