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 A230873 #14 Nov 08 2013 03:40:59 %S A230873 6,14,15,20,28,38,40,42,48,51,52,54,72,78,84,86,88,90,96,102,103,108, %T A230873 110,113,114,120,124,125,126,127,132,138,150,156,162,164,168,174,180, %U A230873 197,198,204,210,216,220,222,224,228,236,238,245,248,250,252,258,262,270,276,279,285,286,295,298,304,306,310,315,316 %N A230873 Numbers that do not appear in A230871. %C A230873 Complement of A230872. %H A230873 Reinhard Zumkeller, <a href="/A230873/b230873.txt">Table of n, a(n) for n = 1..2500</a> %o A230873 (Haskell) %o A230873 a230873 n = a230873_list !! (n-1) %o A230873 a230873_list = f [0..] a230872_list where %o A230873 f (u:us) vs'@(v:vs) = if u == v then f us vs else u : f us vs' %o A230873 -- _Reinhard Zumkeller_, Nov 08 2013 %Y A230873 Cf. A230871, A230872. %K A230873 nonn %O A230873 1,1 %A A230873 _N. J. A. Sloane_, Nov 07 2013