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 A239520 #7 Apr 12 2014 16:26:01 %S A239520 1,4,8,9,49,64,125,128,2187,2197,654481,657721,1442401,1442897, %T A239520 1708249,7252249,7946761,13053769,13082689,21557449,39677401,39702601, %U A239520 86136961,86174089,106729561,106770889,184063489,253987969,302516449,626550961,626651089,844425481 %N A239520 Prime powers (A025475) such that the distance to the nearest prime power is a triangular number (A000217). %Y A239520 Cf. A000217, A025475, A239521, A239522, A239523. %K A239520 nonn %O A239520 1,2 %A A239520 _Alex Ratushnyak_, Mar 20 2014