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 A228485 #15 Aug 24 2013 17:19:11 %S A228485 5,11,23,25,29,41,47,59,83,101,113,121,125,131,137,149,167,173,191, %T A228485 227,239,257,263,281,293,311,317,347,353,383,389,401,419,443,461,479, %U A228485 491,509,529,563,569,587,599,617,625,641,653,659,677,743,761,797,821,839 %N A228485 Odd prime powers p^k such that p is congruent to 2 or 5 mod 9. %C A228485 For any n, the equation x^3 + y^3 = a(n)*z^3 is not solvable in nonzero integers. Therefore, these numbers do not occur in A020898. %D A228485 Henri Cohen, Number Theory. Volume I: Tools and Diophantine Equations, Graduate Texts in Mathematics 239, Springer, 2007, pp. 374-375. %H A228485 Wikipedia, <a href="http://en.wikipedia.org/wiki/Prime_power">Prime power</a> %o A228485 (PARI) forstep(n=3, 839, 2, p=isprimepower(n); if(p>0, m=Mod(round(n^(1/p)), 9); if(m==2||m==5, print1(n, ", ")))); %Y A228485 Cf. A020898, A025473. Subsequence of A061345. %K A228485 nonn %O A228485 1,1 %A A228485 _Arkadiusz Wesolowski_, Aug 23 2013