A136993 - OEIS

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

%S 1,2,4,11,12,21,26,42,46,121,162,276,421,474,642,1474,1621,1662,2162,

%T 2174,4174,4761,4762,4771,6424,6642,11142,16662,21621,24724,26724,

%U 27224,46121,47662,64162,64224,66424,161761,161776,166662,211462,214762,266771,267671,414261,421262,421621,462776,471462,471642,477224,641424,641671,664162,664261

%N Numbers k such that k and k^2 use only the digits 1, 2, 4, 6 and 7.

%C Generated with DrScheme.

%H Jonathan Wellons, <a href="/A136993/b136993.txt">Table of n, a(n) for n = 1..520</a>

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

%e 641612614142421^2 = 411666746626671216217271741241.

%t Module[{c={1,2,4,6,7}},Select[Flatten[Table[FromDigits/@Tuples[c,n],{n,6}]],SubsetQ[c,IntegerDigits[#^2]]&]] (* _Harvey P. Dale_, Aug 15 2015 *)

%K base,nonn

%O 1,2

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