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 A242770 #10 Sep 22 2014 11:37:18 %S A242770 4189,12193,641941,8778073,26822599,11488195489 %N A242770 Composite numbers of the form A242490(n) - 1. %C A242770 a(7) (if it exists) = A242490(k) - 1, k >= 5 * 10^7. - _Hiroaki Yamanouchi_, Sep 22 2014 %e A242770 a(1) = A242490(16) - 1 = 4189 = 59 * 71; %e A242770 a(2) = A242490(21) - 1 = 12193 = 89 * 137; %e A242770 a(3) = A242490(125) - 1 = 641941 = 727 * 883; %e A242770 a(4) = A242490(417) - 1 = 8778073 = 2927 * 2999; %e A242770 a(5) = A242490(675) - 1 = 26822599 = 5081 * 5279; %e A242770 a(6) = A242490(10171) - 1 = 11488195489 = 107183 * 107183. %Y A242770 Cf. A242489, A242490, A242716. %K A242770 nonn,more %O A242770 1,1 %A A242770 _Vladimir Shevelev_ and _Peter J. C. Moses_, May 22 2014 %E A242770 a(6) from _Hiroaki Yamanouchi_, Sep 22 2014