A068237 - OEIS

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A068237

Numerators of arithmetic derivative of 1/n: -A003415(n)/n^2.

0, -1, -1, -1, -1, -5, -1, -3, -2, -7, -1, -1, -1, -9, -8, -1, -1, -7, -1, -3, -10, -13, -1, -11, -2, -15, -1, -2, -1, -31, -1, -5, -14, -19, -12, -5, -1, -21, -16, -17, -1, -41, -1, -3, -13, -25, -1, -7, -2, -9, -20, -7, -1, -1, -16, -23, -22, -31, -1, -23

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,6

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..10000

MAPLE

d:= n-> n*add(i[2]/i[1], i=ifactors(n)[2]):

a:= n-> numer(-d(n)/n^2):

seq(a(n), n=1..80); # Alois P. Heinz, Jun 07 2015

MATHEMATICA

d[n_] := If[n < 2, 0, n Sum[f[[2]]/f[[1]], {f, FactorInteger[n]}]];

a[n_] := Numerator[-d[n]/n^2];

Array[a, 80] (* Jean-François Alcover, Mar 12 2019 *)

PROG

(Python)

from fractions import Fraction

from sympy import factorint

def A068237(n): return -Fraction(sum((Fraction(e, p) for p, e in factorint(n).items())), n).numerator # Chai Wah Wu, Nov 03 2022

CROSSREFS

Cf. A003415, A068238 (denominators).

Sequence in context: A338096 A215010 A136744 * A373363 A083345 A087262

Adjacent sequences: A068234 A068235 A068236 * A068238 A068239 A068240

KEYWORD

sign,frac,look

AUTHOR

Reinhard Zumkeller, Feb 23 2002

STATUS

approved