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 A038558 #13 Jun 19 2017 00:33:34
%S A038558 0,2,4,5,8,9,11,10,16,17,19,18,23,22,20,21,32,33,35,34,39,38,36,37,47,
%T A038558 46,44,45,40,41,43,42,64,65,67,66,71,70,68,69,79,78,76,77,72,73,75,74,
%U A038558 95,94,92,93,88,89,91,90,80,81,83,82,87,86,84,85,128,129,131,130,135,134
%N A038558 Smallest number with derivative n.
%H A038558 Reinhard Zumkeller, <a href="/A038558/b038558.txt">Table of n, a(n) for n = 0..10000</a>
%t A038558 dtn[ L_ ] := Fold[ 2#1+#2&, 0, L ]; h[ n_ ] := dtn[ {1}~Join~Table[ Mod[ 1+Apply[ Plus, Take[ IntegerDigits[ n, 2 ], k ] ], 2 ], {k, 1, Length[ IntegerDigits[ n, 2 ] ]} ] ]; Table[ h[ n ], {n, 100} ]
%o A038558 (Haskell)
%o A038558 import Data.List (elemIndex)
%o A038558 import Data.Maybe (fromJust)
%o A038558 a038558 = fromJust . (`elemIndex` a038554_list)
%o A038558 -- _Reinhard Zumkeller_, Mar 06 2013
%Y A038558 Cf. A038554-A038556.
%K A038558 nonn,nice,easy
%O A038558 0,2
%A A038558 _N. J. A. Sloane_
%E A038558 More terms from _Erich Friedman_
%E A038558 a(0)=0 added and offset adjusted by _Reinhard Zumkeller_, Mar 06 2013