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 A023734 #10 Feb 23 2019 21:47:24 %S A023734 3,8,13,15,16,17,19,23,28,33,38,40,41,42,44,48,53,58,63,65,66,67,69, %T A023734 73,75,76,77,79,80,81,82,84,85,86,87,89,95,96,97,99,103,108,113,115, %U A023734 116,117,119,123,128,133,138,140,141,142,144,148,153,158 %N A023734 Numbers with a single 3 in their base-5 expansion. %H A023734 Nathaniel Johnston, <a href="/A023734/b023734.txt">Table of n, a(n) for n = 1..10000</a> %p A023734 seq(`if`(numboccur(3,convert(n,base,5))=1,n,NULL),n=0..200); # _Nathaniel Johnston_, Jun 27 2011 %t A023734 Select[ Range[ 150 ], (Count[ IntegerDigits[ #, 5 ], 3 ]==1)& ] %Y A023734 Cf. A023733, A023735. %K A023734 nonn,base,easy %O A023734 1,1 %A A023734 _Olivier Gérard_