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 A074791 #25 Nov 06 2024 08:36:50
%S A074791 6,18,20,21,33,42,54,63,66,77,100,110,120,156,162,189,198,272,294,336,
%T A074791 342,363,377,435,486,500,506,559,567,594,600,610,629,685,703,812,847,
%U A074791 880,924,930,957,1067,1166,1210,1243,1247,1287,1320,1332,1458,1590,1640
%N A074791 Numbers k such that k does not divide the denominator of the k-th harmonic number.
%C A074791 k such that A064169(k) is different from A027612(k).
%C A074791 Also k such that A096617(k) is different from A001008(k). - _Alexander Adamchuk_, Jun 26 2006
%C A074791 This sequence contains A036689(k) for all k > 1. - _Wouter van Doorn_, Nov 06 2024
%H A074791 Amiram Eldar, <a href="/A074791/b074791.txt">Table of n, a(n) for n = 1..2000</a>
%F A074791 Is a(n) asymptotic to c*n^2 0.5<c<0.7 ?
%F A074791 a(n) < 2*n^2*log(n)^2 for all n > 2. This follows from the fact that for all k > 1 there exists an n such that A036689(k) is equal to A074791(n). - _Wouter van Doorn_, Nov 06 2024
%t A074791 Select[ Range[1700], Mod[ Denominator[ HarmonicNumber[ # ]], # ] != 0 &] (* _Robert G. Wilson v_, Sep 28 2005 *)
%t A074791 seq = {}; s = 0; Do[s += 1/n; If[! Divisible[Denominator[s], n], AppendTo[seq, n]], {n, 1, 2000}]; seq (* _Amiram Eldar_, Dec 01 2020 *)
%Y A074791 Cf. A027612, A064169.
%Y A074791 Cf. A096617, A001008.
%K A074791 nonn
%O A074791 1,1
%A A074791 _Benoit Cloitre_, Sep 07 2002
%E A074791 Better description and more terms from _Robert G. Wilson v_, Sep 28 2005