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 A099377 Numerators of the harmonic means of the divisors of the positive integers. 49
 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 (Python) from sympy import gcd, divisor_sigma def A099377(n): return (lambda x, y: y*n//gcd(x, y*n))(divisor_sigma(n), divisor_sigma(n, 0)) # Chai Wah Wu, Oct 20 2021 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 May 28 00:20 EDT 2024. Contains 372900 sequences. (Running on oeis4.)