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 A290869 #20 Jul 10 2019 03:02:38 %S A290869 4095,32767,65535,67053,262143,265720,531440,1048575,2097151,4381419, %T A290869 5592405,7174453,9808617,11184810,13938267,14348906,16777215,19617234, %U A290869 21523360,29425851,39234468,43046720,48686547,49043085,58851702,61035156,68660319,71270178 %N A290869 Numbers that are repdigits with length > 2 in more than two bases. %C A290869 Most of the terms of A167783 are repdigits with length > 2 in only two bases. %C A290869 For any b > 1 and k > 2, b^(4*k)-1 is a repdigit with length > 2 in bases b, b^2 and b^4; hence this sequence is infinite. - _Rémy Sigrist_, Aug 19 2017 %H A290869 Rémy Sigrist, <a href="/A290869/b290869.txt">Table of n, a(n) for n = 1..777</a> %H A290869 Rémy Sigrist, <a href="/A290869/a290869.txt">C# program for A290869</a> %H A290869 Rémy Sigrist, <a href="/A290869/a290869_1.txt">C++ program for A290869</a> %e A290869 67053 is a repdigit with more than 2 digits in three bases: [31,31,31]_46, [21,21,21]_56, [3,3,3]_149. %o A290869 (PARI) isok(n)=my(nb = 0); for (b=2, n-1, d = digits(n, b); if ((#d > 2) && (#Set(d) == 1), nb++); if (nb > 2, return (1)); ); return (0); %o A290869 (C#) See Links section. %o A290869 (C++) See Links section. %Y A290869 Subsequence of A167783. %K A290869 nonn,base %O A290869 1,1 %A A290869 _Michel Marcus_, Aug 13 2017 %E A290869 More terms from _Giovanni Resta_, Aug 13 2017