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 A261793 #7 Feb 15 2016 12:20:51 %S A261793 1,3,4,5,6,7,8,9,10,12,15,17,19,21,24,25,26,27,28,29,30,31,33,34,35, %T A261793 36,37,38,39,40,41,43,44,45,46,47,48,49,50,51,53,54,55,56,57,58,59,60, %U A261793 61,63,64,65,66,67,68,69,70,71,73,74,75,76,77,78,79,80,81 %N A261793 Successively add the smallest number that is not a substring in decimal representation. %H A261793 Reinhard Zumkeller, <a href="/A261793/b261793.txt">Table of n, a(n) for n = 1..10000</a> %o A261793 (Haskell) %o A261793 a261793 n = a261793_list !! (n-1) %o A261793 a261793_list = iterate (\x -> x + a261794 x) 1 %Y A261793 Cf. A031298, A261794, A261795 (first differences), A261806, A260273, A261786 %K A261793 nonn,base %O A261793 1,2 %A A261793 _Reinhard Zumkeller_, Sep 01 2015