Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #11 Jul 05 2021 02:53:57
%S 0,1,4,10,40,100,400,1000,1071,4000,7776,10000,10710,10771,40000,
%T 77760,100000,106771,106776,107100,107710,400000,777600,1000000,
%U 1007046,1067710,1067760,1071000,1077100,1077776,4000000,6406771,7771774,7776000,10000000,10070460,10677100,10677600,10710000,10771000,10777760,40000000,64067710
%N Numbers k such that k and k^2 use only the digits 0, 1, 4, 6 and 7.
%C Generated with DrScheme.
%H Jonathan Wellons, <a href="/A136860/b136860.txt">Table of n, a(n) for n = 1..316</a>
%H Jonathan Wellons, <a href="https://web.archive.org/web/20090206165028/http://jonathanwellons.com/shared-digits/">Tables of Shared Digits</a>
%e 646076401416771^2 = 417414716467644616616040066441.
%t With[{c={0,1,4,6,7}},Select[FromDigits/@Tuples[c,8],SubsetQ[ c,IntegerDigits[ #^2]]&]] (* _Harvey P. Dale_, Jul 16 2020 *)
%Y Cf. A000290.
%K base,nonn
%O 1,3
%A Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008