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 A046681 #17 May 08 2021 22:57:10 %S A046681 1,2,8,9,18,64,72,128,625,729,1024,1152,1250,1458,4096,5000,5625,5832, %T A046681 6561,8192,9216,11250,13122,15625,31250,32768,40000,45000,46656,52488, %U A046681 59049,65536,80000,93312,117649,118098,125000,235298,262144,294912 %N A046681 Numbers k such that the number of divisors of k and sum of 4th powers of divisors of k are relatively prime. %C A046681 It can be shown that this is a subsequence of A028982. %H A046681 Amiram Eldar, <a href="/A046681/b046681.txt">Table of n, a(n) for n = 1..5000</a> %t A046681 Select[Range[300000],CoprimeQ[DivisorSigma[0,#],DivisorSigma[4,#]]&] (* _Harvey P. Dale_, May 30 2012 *) %o A046681 (PARI) isok(n) = gcd(sigma(n, 4), numdiv(n)) == 1; \\ _Michel Marcus_, Sep 24 2019 %Y A046681 Cf. A028982, A046678, A046679, A046680, A046683, A046685. %K A046681 nonn %O A046681 1,2 %A A046681 _Labos Elemer_