A074791 - OEIS

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A074791

Numbers k such that k does not divide the denominator of the k-th Harmonic number.

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

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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

Amiram Eldar, Table of n, a(n) for n = 1..2000

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 *)