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 A043457 #11 Apr 24 2021 20:49:11 %S A043457 1,9,11,12,13,14,15,16,17,19,28,37,46,55,64,73,81,83,84,85,86,87,88, %T A043457 89,99,101,102,103,104,105,106,107,108,110,111,112,113,114,115,116, %U A043457 117,119,120,121,122,123,124,125,126,128,129,130 %N A043457 Numbers having one 1 in base 9. %t A043457 Select[Range[150],DigitCount[#,9,1]==1&] (* _Harvey P. Dale_, Aug 15 2011 *) %Y A043457 Cf. A007095. %K A043457 nonn,base %O A043457 1,2 %A A043457 _Clark Kimberling_