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 A136911 Numbers k such that k and k^2 use only the digits 0, 2, 5 and 6. 1

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

%S 0,5,25,50,225,250,255,500,505,2250,2500,2550,5000,5005,5025,5050,

%T 22500,25000,25005,25025,25500,25505,50000,50005,50025,50050,50225,

%U 50250,50255,50500,225000,250000,250005,250050,250250,255000,255050,256255,500000,500005,500025,500050,500225,500250,500255,500500,500505,502250,502500,502550

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

%C Generated with DrScheme.

%H Jonathan Wellons, <a href="/A136911/b136911.txt">Table of n, a(n) for n = 1..1036</a>

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

%e 5005050005005^2 = 25050525552600550525050025.

%t odQ[n_]:=Module[{idn2=IntegerDigits[n^2]},And@@Table[MemberQ[{0,2,5,6}, idn2[[i]]],{i,Length[idn2]}]]; Union[Flatten[Table[Select[FromDigits/@ Tuples[{0,2,5,6},d],odQ],{d,6}]]] (* _Harvey P. Dale_, Jul 17 2012 *)

%K base,nonn

%O 1,2

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

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Last modified June 19 23:45 EDT 2024. Contains 373510 sequences. (Running on oeis4.)