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 A179891 Composites h such that antiharmonic mean B(h) of the numbers k < h such that gcd(k, h) = 1 is not integer. 22
 4, 6, 8, 9, 12, 14, 15, 16, 18, 20, 21, 24, 25, 26, 27, 28, 30, 32, 33, 35, 36, 38, 39, 40, 42, 44, 45, 48, 49, 50, 51, 52, 54, 56, 57, 60, 62, 63, 64, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81, 84, 86, 87, 88, 90, 92, 93, 95, 96, 98, 99, 100, 102, 104, 105, 108, 111 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Composites h such that B(h) = A053818(h) / A023896(h) = A175505(h) / A175506(h) is not integer. Composites h such that A175506(h) > 1. Subsequence of A179872. Union a(n) + A007645 = A179872. LINKS G. C. Greubel, Table of n, a(n) for n = 1..1749 EXAMPLE a(6) = 14 because B(14) = A053818(14) / A023896(14) = 406/42 = 29/3 (not integer). MATHEMATICA f[n_] := 2 Plus @@ (Select[ Range@n, GCD[ #, n] == 1 &]^2)/(n*EulerPhi@n); Select[ Range@ 111, ! PrimeQ@# && ! IntegerQ@f@# &] (* Robert G. Wilson v, Aug 02 2010 *) CROSSREFS Cf. A179871, A179872, A179873, A179874, A179875, A179876, A179877, A179878, A179879, A179880, A179882, A179883, A179884, A179885, A179886, A179887, A179890. Sequence in context: A176539 A285256 A013920 * A064590 A259315 A211771 Adjacent sequences:  A179888 A179889 A179890 * A179892 A179893 A179894 KEYWORD nonn AUTHOR Jaroslav Krizek, Jul 30 2010 EXTENSIONS More terms from Robert G. Wilson v, Aug 02 2010 STATUS approved

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Last modified August 12 03:34 EDT 2020. Contains 336436 sequences. (Running on oeis4.)