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 A031961 #13 Aug 10 2021 18:47:00 %S A031961 83,84,85,86,87,88,89,99,102,103,104,105,106,107,108,110,112,113,114, %T A031961 115,116,117,119,120,122,123,124,125,126,128,129,130,132,133,134,135, %U A031961 137,138,139,140,142,143,144,146,147,148,149 %N A031961 Numbers with exactly three distinct base-9 digits. %Y A031961 Cf. A007095. %K A031961 nonn,base %O A031961 1,1 %A A031961 _Clark Kimberling_