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 A031466 #14 Jul 04 2021 14:11:29 %S A031466 3,7,11,13,14,23,27,29,30,39,43,45,46,51,53,54,57,58,60,79,87,91,93, %T A031466 94,103,107,109,110,115,117,118,121,122,124,143,151,155,157,158,167, %U A031466 171,173,174,179,181,182,185,186,188,199,203,205 %N A031466 Numbers whose base-4 representation has one fewer 0 than 3's. %C A031466 Numbers n such that A160383(n) - A160380(n) = 1. - _Robert Israel_, Jun 05 2018 %H A031466 Robert Israel, <a href="/A031466/b031466.txt">Table of n, a(n) for n = 1..10000</a> %p A031466 filter:= proc(n) local L; %p A031466 L:= convert(n,base,4); %p A031466 numboccur(3,L) - numboccur(0,L)=1 %p A031466 end proc: %p A031466 select(filter, [$1..300]); # _Robert Israel_, Jun 05 2018 %t A031466 Select[Range[210],DigitCount[#,4,0]==DigitCount[#,4,3]-1&] (* _Harvey P. Dale_, Dec 16 2011 *) %Y A031466 Cf. A007090, A160380, A160383. %K A031466 nonn,base %O A031466 1,1 %A A031466 _Clark Kimberling_