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 A136931 #14 Aug 11 2025 11:00:22
%S A136931 0,6,8,60,80,600,800,6000,6638,6808,6844,8000,60000,60406,60688,66380,
%T A136931 66808,68080,68440,80000,600000,604060,606880,663800,668080,680800,
%U A136931 684400,800000,6000000,6003406,6004006,6040600,6068800,6638000,6680800,6808000,6844000,8000000,60000000,60034060,60040060,60406000,60688000,66363008,66380000
%N A136931 Numbers k such that k and k^2 use only the digits 0, 3, 4, 6 and 8.
%C A136931 Generated with DrScheme.
%H A136931 Jonathan Wellons, <a href="/A136931/b136931.txt">Table of n, a(n) for n = 1..378</a>
%H A136931 J. Wellons, <a href="https://web.archive.org/web/20090206165028/http://jonathanwellons.com/shared-digits/">Tables of Shared Digits</a> [archived]
%e A136931 683084686436344^2 = 466604688843838404646364086336.
%t A136931 s={0,3,4,6,8}; Select[Range[0,10^6], SubsetQ[s, Sort[DeleteDuplicates[IntegerDigits[#]]]] && SubsetQ[s, Sort[DeleteDuplicates[IntegerDigits[#^2]]]] &] (* _Stefano Spezia_, Aug 11 2025 *)
%Y A136931 See also A058429-A058430. - _M. F. Hasler_, Jan 24 2008
%K A136931 base,nonn
%O A136931 1,2
%A A136931 Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008