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A068238 Denominators of arithmetic derivative of 1/n: -A003415(n)/n^2. 3
1, 4, 9, 4, 25, 36, 49, 16, 27, 100, 121, 9, 169, 196, 225, 8, 289, 108, 361, 50, 441, 484, 529, 144, 125, 676, 27, 49, 841, 900, 961, 64, 1089, 1156, 1225, 108, 1369, 1444, 1521, 400, 1681, 1764, 1849, 121, 675, 2116, 2209, 144, 343, 500, 2601, 338, 2809, 36 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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-> denom(-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_] := Denominator[-d[n]/n^2];

Array[a, 80] (* Jean-Fran├žois Alcover, Mar 12 2019 *)

CROSSREFS

Cf. A003415, A068237 (numerators).

Sequence in context: A087320 A087321 A053143 * A280441 A255290 A087369

Adjacent sequences:  A068235 A068236 A068237 * A068239 A068240 A068241

KEYWORD

nonn,frac

AUTHOR

Reinhard Zumkeller, Feb 23 2002

STATUS

approved

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Last modified February 26 12:43 EST 2020. Contains 332280 sequences. (Running on oeis4.)