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 A225389 #7 May 08 2013 23:36:02 %S A225389 781370209,59015782001929,109012413691801,185341023228001, %T A225389 275502533796361,315952509152809,613721000732449,1579642847367841, %U A225389 3182047597748881,5927491050020401,13602074755852489,22706626517726761 %N A225389 Prime powers (A025475) representable as (p+q)/2, where p and q are distinct prime powers, in two or more ways. %C A225389 Prime powers p such that there are x and y such that p+x, p-x, p+y, p-y are four distinct prime powers. %C A225389 First 12 terms are squares of prime numbers. %C A225389 Conjecture: the sequence is infinite. %Y A225389 Cf. A025475, A225388. %K A225389 nonn,hard,more %O A225389 1,1 %A A225389 _Alex Ratushnyak_, May 05 2013