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 A167886 #4 Mar 30 2012 18:52:35 %S A167886 2,3,3,7,11,15,21,27,31,34,39,45,51,55,60,63,68,75,78,83,87,100,103, %T A167886 109,119,125,130,133,138,144,154,159,171,182,185,189,195,205,209,214, %U A167886 220,226,230,239,252,256,260,273,278,287,291,296,303,308,313,315,320,327 %N A167886 n-th single or isolated number minus n-th non-single or nonisolated number. %F A167886 a(n)=A167706(n)-A167707(n). %e A167886 a(1)=2-0=2, a(2)=4-1=3, a(3)=6-3=3, a(4)=12-5=7. %Y A167886 Cf. A167706, A167707. %K A167886 nonn %O A167886 1,1 %A A167886 _Juri-Stepan Gerasimov_, Nov 14 2009 %E A167886 All numbers > 68 corrected by _R. J. Mathar_, May 30 2010