login
A074791
Numbers k such that k does not divide the denominator of the k-th Harmonic number.
8
6, 18, 20, 21, 33, 42, 54, 63, 66, 77, 100, 110, 120, 156, 162, 189, 198, 272, 294, 336, 342, 363, 377, 435, 486, 500, 506, 559, 567, 594, 600, 610, 629, 685, 703, 812, 847, 880, 924, 930, 957, 1067, 1166, 1210, 1243, 1247, 1287, 1320, 1332, 1458, 1590, 1640
OFFSET
1,1
COMMENTS
k such that A064169(k) is different from A027612(k).
Also k such that A096617(k) is different from A001008(k). - Alexander Adamchuk, Jun 26 2006
LINKS
FORMULA
Is a(n) asymptotic to c*n^2 0.5<c<0.7 ?
MATHEMATICA
Select[ Range[1700], Mod[ Denominator[ HarmonicNumber[ # ]], # ] != 0 &] (* Robert G. Wilson v *)
seq = {}; s = 0; Do[s += 1/n; If[! Divisible[Denominator[s], n], AppendTo[seq, n]], {n, 1, 2000}]; seq (* Amiram Eldar, Dec 01 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Sep 07 2002
EXTENSIONS
Better description and more terms from Robert G. Wilson v, Sep 28 2005
STATUS
approved