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Numbers k such that k and k^2 use only the digits 0, 6, 7, 8 and 9.
1

%I #10 Apr 12 2024 09:51:27

%S 0,887,8870,8886,8887,87676,87687,88700,88860,88870,88887,89867,

%T 876760,876870,887000,887676,888600,888700,888870,898670,989897,

%U 7788887,7796076,8767600,8768700,8870000,8876760,8886000,8887000,8888700,8986700,8998667,9888887,9898970,77888870,77960760,87676000,87687000,87787687,87788887,88700000

%N Numbers k such that k and k^2 use only the digits 0, 6, 7, 8 and 9.

%C Generated with DrScheme.

%H Jonathan Wellons, <a href="/A136966/b136966.txt">Table of n, a(n) for n = 1..413</a>

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

%e 898709006786897^2 = 807677878879890878007970888609.

%t With[{c={0,6,7,8,9}},Select[FromDigits/@Tuples[c,8],SubsetQ[ c, IntegerDigits[ #^2]]&]] (* _Harvey P. Dale_, Jan 31 2020 *)

%K base,nonn

%O 1,2

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