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 A239584 #13 Apr 06 2014 08:48:27 %S A239584 8,9,121,343,2209 %N A239584 Prime powers p^q (A025475) such that either x divides y, or y divides x, where x and y are the distances from p^q to the nearest prime powers above and below p^q. %e A239584 The nearest prime powers above and below 121 are 81 and 125, because 125-121=4 divides 121-81=40, 121 is the sequence. %Y A239584 Cf. A025475, A239524, A239879. %K A239584 nonn,hard,more %O A239584 1,1 %A A239584 _Alex Ratushnyak_, Mar 21 2014