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 A031957 #13 Aug 10 2021 14:46:00 %S A031957 27,28,29,35,38,39,40,42,44,45,47,48,51,53,54,55,58,59,65,66,69,70,71, %T A031957 73,76,77,79,80,82,84,85,86,89,95,96,97,101,102,103,105,107,108,110, %U A031957 111,113,115,116,117,127,128,129,132,133,134 %N A031957 Numbers with exactly three distinct base-5 digits. %Y A031957 Cf. A007091. %K A031957 nonn,base %O A031957 1,1 %A A031957 _Clark Kimberling_