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 A343217 #14 Aug 30 2025 10:25:44
%S A343217 3,5,6,7,8,10,11,12,14,15,17,19,20,21,22,23,24,26,27,28,29,30,31,32,
%T A343217 33,34,35,38,39,40,41,42,43,44,45,46,47,48,51,52,53,54,55,56,57,58,59,
%U A343217 60,62,63,65,66,67,68,69,70,71,72,74,75,76,77,78,79,80,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,98,99
%N A343217 Numbers k such that A003415(sigma(k)) >= k, where A003415(x) gives the arithmetic derivative of x.
%H A343217 Antti Karttunen, <a href="/A343217/b343217.txt">Table of n, a(n) for n = 1..10000</a>
%H A343217 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%t A343217 Select[Range[100], If[#2 < 2, 0, #2 Total[#2/#1 & @@@ FactorInteger[#2]]] >= #1 & @@ {#, DivisorSigma[1, #]} &] (* _Michael De Vlieger_, Apr 08 2021 *)
%o A343217 (PARI)
%o A343217 A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
%o A343217 isA343217(n) = (A003415(sigma(n))>=n);
%Y A343217 Cf. A000203, A003415, A342925, A343216 (complement).
%Y A343217 Disjoint union of A342021 and A343218.
%Y A343217 Positions of nonnegative terms in A342926.
%K A343217 nonn,changed
%O A343217 1,1
%A A343217 _Antti Karttunen_, Apr 08 2021