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 A239523 #6 Apr 12 2014 16:26:41 %S A239523 1,25,27,32,128,512,2048,8192,32768,562949953421312 %N A239523 Prime powers (A025475) such that the distances to the two nearest prime powers are primes. %C A239523 A subsequence of A239522. %C A239523 a(4)...a(10) are powers of 2, a(10) = 2^49. %Y A239523 Cf. A025475, A239520 - A239522. %K A239523 nonn,more %O A239523 1,2 %A A239523 _Alex Ratushnyak_, Mar 20 2014