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A211178 Denominator of sum_{k=1..n}(-1)^k/phi(k) where phi=A000010 1
1, 1, 2, 1, 4, 4, 12, 3, 6, 12, 60, 30, 60, 20, 40, 20, 80, 240, 720, 720, 720, 144, 1584, 1584, 7920, 7920, 7920, 7920, 55440, 55440, 11088, 5544, 27720, 55440, 55440, 55440, 55440, 6160, 18480, 2310 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..40.

O. Bordelles, B. Cloitre, An Alternating Sum Involving the Reciprocal of Certain Multiplicative Functions, J. Int. Seq. 16 (2013) #13.6.3

FORMULA

A211177(n)/a(n)=c*log(n)+O(1) with a suitable constant c (see ref).

PROG

(PARI) a(n)=denominator(sum(k=1, n, (-1)^k/eulerphi(k)))

CROSSREFS

A211177 (numerators)

Sequence in context: A095293 A034409 A209478 * A048049 A212716 A057772

Adjacent sequences:  A211175 A211176 A211177 * A211179 A211180 A211181

KEYWORD

nonn,frac

AUTHOR

Benoit Cloitre, Feb 01 2013

STATUS

approved

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Last modified August 10 02:02 EDT 2020. Contains 336365 sequences. (Running on oeis4.)