This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A137003 #13 May 10 2024 08:51:31
%S A137003 1,5,11,15,16,25,125,511,515,516,1125,2261,5125,12511,12515,25525,
%T A137003 51211,125125,5162515,51626211,125162515,5162525125
%N A137003 Numbers k such that k and k^2 use only the digits 1, 2, 5 and 6.
%C A137003 Generated with DrScheme.
%C A137003 Subsequence of A137004 and A137007. - _M. F. Hasler_, Jan 24 2008
%H A137003 Jonathan Wellons, <a href="https://web.archive.org/web/20090206165028/http://jonathanwellons.com/shared-digits/">Tables of Shared Digits</a> [archived]
%e A137003 5162525125^2 = 26651665666256265625.
%t A137003 okQ[n_]:=With[{idn=IntegerDigits[n^2]},And@@Table[MemberQ[{1,2,5,6}, idn[[i]]],{i,Length[idn]}]]; Flatten[Table[Select[ FromDigits/@ Tuples[{1,2,5,6},k],okQ],{k,10}]] (* _Harvey P. Dale_, Jul 07 2012 *)
%K A137003 base,nonn,more
%O A137003 1,2
%A A137003 Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008