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 A255772 #14 Mar 07 2015 10:16:18 %S A255772 7,3,13,241,97,673,193,22253377,18446744069414584321,769, %T A255772 442499826945303593556473164314770689,349621839326921795694385454593, %U A255772 331192380488114152600457428497953408512758882817,212780015855109121 %N A255772 Start with 7; thereafter, in order of appearance, the prime factors of A220294. %C A255772 A220161(n-1) = the product of the first A255770(n) terms. %D A255772 Arthur Engel, Problem-Solving Strategies, Springer, 1998, pages 121-122 (E3, said to be a "recent competition problem from the former USSR"). %H A255772 Hans Havermann, <a href="/A255772/b255772.txt">Table of n, a(n) for n = 1..22</a> %H A255772 factordb, <a href="http://factordb.com/index.php?query=1+-+2%5E%282%5E%28n-1%29%29+%2B+2%5E%282%5En%29">First 20 factorizations of A220294</a> %Y A255772 Cf. A220161, A220294, A255770, A255771. %K A255772 nonn %O A255772 1,1 %A A255772 _Hans Havermann_, Mar 06 2015