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 A248021 #31 Apr 14 2020 04:27:45 %S A248021 196,216,441,1000,1521,1728,1764,2744,3249,3375,3969,4900,5832,5929, %T A248021 6084,7056,7776,8000,8649,9604,9801,10648,11025,12321,12544,12996, %U A248021 13689,13824,15376,15876,16641,17576,17689,21952,23716,24025,24336,25921,27000,28224,29241,33124,33489,34596 %N A248021 Perfect powers which are not coprime to the sum of their divisors. %C A248021 Intersection of A001597 and A069059. - _Michel Marcus_, Oct 25 2014 %H A248021 Amiram Eldar, <a href="/A248021/b248021.txt">Table of n, a(n) for n = 1..10000</a> %t A248021 perfectPowerQ[n_] := n == 1 || GCD @@ FactorInteger[n][[All, 2]] > 1; Select[ Range@ 35000, perfectPowerQ[ #] && GCD[#, DivisorSigma[1, #]] > 1 &] %o A248021 (PARI) for(n=1, 1e5, if(ispower(n), if(gcd(n, sigma(n)) > 1, print1(n, ", ")))) \\ _Felix Fröhlich_, Oct 25 2014 %Y A248021 Cf. A001597 (perfect powers), A069059 (gcd(n, sigma(n)) != 1). %K A248021 nonn,easy %O A248021 1,1 %A A248021 _Robert G. Wilson v_, Sep 29 2014