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 A259534 #34 Jul 04 2015 23:51:52
%S A259534 5,29,509,131069,8589934589,5506148072189,1509659159988837629,
%T A259534 90050548615896750734368618889875709,
%U A259534 111565998552535226317138856424609779410946920431869,270528914968139650436266764640655805238384653911572627709
%N A259534 a(n) = -1 + 2 * product_{i=0..n} A093179(i), where A093179(i) is the smallest prime factor of 2^(2^i) + 1.
%C A259534 For any k >= 1, numbers of the form (k*a(n) + k - 1)*2^m - 1 are composite for all m < 2^(n+1).
%C A259534 Many terms are in common with A006285 (de Polignac numbers).
%o A259534 (PARI) a(n) = - 1 + 2 * prod(k=0, n, factor(2^(2^k)+1)[1,1]); \\ _Michel Marcus_, Jul 04 2015
%Y A259534 Cf. A006285, A093179.
%K A259534 nonn
%O A259534 0,1
%A A259534 _Arkadiusz Wesolowski_, Jul 02 2015