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Numbers k such that k and k^2 use only the digits 0, 2, 4, 5 and 6.
1

%I #9 Apr 12 2024 09:51:26

%S 0,2,5,20,25,45,50,65,200,205,225,245,250,255,450,500,502,505,650,665,

%T 2000,2005,2050,2065,2242,2245,2250,2450,2500,2502,2550,4500,5000,

%U 5002,5005,5020,5025,5045,5050,5065,6500,6650,6665,20000,20005,20050,20065,20500,20505,20602,20605,20650,22420,22450,22500,24500,24605,25000,25005,25020,25025

%N Numbers k such that k and k^2 use only the digits 0, 2, 4, 5 and 6.

%C Generated with DrScheme.

%H Jonathan Wellons, <a href="/A136898/b136898.txt">Table of n, a(n) for n = 1..1144</a>

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

%e 506204065^2 = 256242555422524225.

%t With[{c={0,2,4,5,6}},Select[FromDigits/@Tuples[c,5],SubsetQ[c, IntegerDigits[ #^2]]&]] (* _Harvey P. Dale_, May 12 2018 *)

%K base,nonn

%O 1,2

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