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Numbers k such that k and k^2 use only the digits 1, 3, 5, 6 and 8.
1

%I #9 Apr 12 2024 09:51:27

%S 1,6,56,81,816,1156,1881,3656,8131,8166,36316,81556,116881,188556,

%T 581666,813381,1163566,1168581,1366881,1888566,5613656,11555881,

%U 11668381,13551316,18313556,18353656,36316156,36556331,56138816,56156331,58153816,58168581,115555881,135318581,135513316,183353656,368356666,368535631,558138566

%N Numbers k such that k and k^2 use only the digits 1, 3, 5, 6 and 8.

%C Generated with DrScheme.

%H Jonathan Wellons, <a href="/A137034/b137034.txt">Table of n, a(n) for n = 1..185</a>

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

%e 816588565653816^2 = 666816885556556563855555361856.

%t With[{c={1,3,5,6,8}},Table[Select[FromDigits/@Tuples[c,n],SubsetQ[ c, IntegerDigits[ #^2]]&],{n,9}]]//Flatten (* _Harvey P. Dale_, Jul 21 2016 *)

%K base,nonn

%O 1,2

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