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 A109850 #4 Dec 05 2013 19:57:00 %S A109850 1,2,3,4,5,8,9,12,15,16,17,32,33,60,63,64,65,104,120,125,128,129,252, %T A109850 255,256,257,512,513,912,972,1008,1017,1020,1023,1024,1025,2000,2025, %U A109850 2040,2045,2048,2049,4092,4095,4096,4097,7712,8160,8177,8192,8193,16380 %N A109850 Numbers n such that a(A109849(n)) = n. %C A109850 2^n and 2^n + 1 seem to be in the sequence for all n. - _Joshua Zucker_, May 04 2006 %Y A109850 Cf. A109849. %K A109850 nonn %O A109850 1,2 %A A109850 _Amarnath Murthy_, Jul 06 2005 %E A109850 More terms from _Joshua Zucker_, May 04 2006