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A099377 Numerators of the harmonic means of the divisors of the positive integers. 7
1, 4, 3, 12, 5, 2, 7, 32, 27, 20, 11, 18, 13, 7, 5, 80, 17, 36, 19, 20, 21, 22, 23, 16, 75, 52, 27, 3, 29, 10, 31, 64, 11, 68, 35, 324, 37, 38, 39, 32, 41, 7, 43, 22, 45, 23, 47, 120, 49, 100, 17, 156, 53, 18, 55, 56, 57, 116, 59, 30, 61, 31, 189, 448, 65, 11, 67, 68, 23, 35 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Ore's Conjecture

EXAMPLE

1, 4/3, 3/2, 12/7, 5/3, 2, 7/4, 32/15, ...

MATHEMATICA

f[n_] := DivisorSigma[0, n]/Plus @@ (1/Divisors@n); Numerator@ Array[f, 70] (* Robert G. Wilson v, Aug 04 2010 *)

Table[Numerator[DivisorSigma[0, n]/DivisorSigma[-1, n]], {n, 70}] (* Ivan Neretin, Nov 13 2016 *)

PROG

(PARI) a(n) = my(d=divisors(n)); numerator(#d/sum(k=1, #d, 1/d[k])); \\ Michel Marcus, Nov 13 2016

CROSSREFS

Cf. A099378.

Sequence in context: A271888 A271098 A269718 * A121844 A091512 A106285

Adjacent sequences:  A099374 A099375 A099376 * A099378 A099379 A099380

KEYWORD

nonn,frac

AUTHOR

Eric W. Weisstein, Oct 13 2004

EXTENSIONS

More terms from Robert G. Wilson v, Aug 04 2010

STATUS

approved

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Last modified April 4 05:34 EDT 2020. Contains 333212 sequences. (Running on oeis4.)