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 A092873 #11 Oct 07 2017 07:35:26 %S A092873 3,5,11,17,41,83,137,257,641,1097,17477,65537,140417,557057,2384897, %T A092873 4227137,35946497,71304257,541073537,2281701377,2336497860617, %U A092873 600470787982337,2278291849363457,4538923050090497,38280596832649217 %N A092873 Prime factors of the odd terms of A007755. %C A092873 Catlin shows that if A007755(n) is odd and composite, then its factors are among the A007755(k), k < n. Note that the five Fermat primes are in this sequence. %H A092873 T. D. Noe, <a href="/A092873/b092873.txt">Table of n, a(n) for n=1..288</a> (odd primes in the first 1000 terms of A007755) %H A092873 P. A. Catlin, <a href="http://www.jstor.org/stable/2316857">Concerning the iterated phi-function</a>, Amer Math. Monthly 77 (1970), pp. 60-61. %K A092873 nonn %O A092873 1,1 %A A092873 _T. D. Noe_, Mar 08 2004 %E A092873 More terms from _T. D. Noe_, Aug 03 2005 %E A092873 a(21) corrected and comment deleted by _T. D. Noe_, Nov 18 2008