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 A136820 #7 Apr 12 2024 09:51:26 %S A136820 0,1,2,10,11,12,20,21,22,100,101,102,110,120,122,200,201,202,210,220, %T A136820 221,1000,1001,1002,1010,1011,1012,1020,1021,1022,1100,1101,1102,1200, %U A136820 1201,1202,1220,1422,1488,2000,2001,2002,2010,2011,2012,2020,2021,2022,2100,2101,2102,2200,2201,2202,2210,2848,4488,10000,10001,10002,10010,10011,10012,10020 %N A136820 Numbers k such that k and k^2 use only the digits 0, 1, 2, 4 and 8. %C A136820 Generated with DrScheme. %H A136820 Jonathan Wellons, <a href="/A136820/b136820.txt">Table of n, a(n) for n = 1..1047</a> %H A136820 J. Wellons, <a href="https://web.archive.org/web/20090206165028/http://jonathanwellons.com/shared-digits/">Tables of Shared Digits</a> [archived] %e A136820 20284201^2 = 411448810208401. %K A136820 base,nonn %O A136820 1,3 %A A136820 Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008