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A250097 Denominator of the harmonic mean of the prime factors, without multiplicity, of n. 2
1, 1, 1, 1, 5, 1, 1, 1, 7, 1, 5, 1, 9, 4, 1, 1, 5, 1, 7, 5, 13, 1, 5, 1, 15, 1, 9, 1, 31, 1, 1, 7, 19, 6, 5, 1, 21, 8, 7, 1, 41, 1, 13, 4, 25, 1, 5, 1, 7, 10, 15, 1, 5, 8, 9, 11, 31, 1, 31, 1, 33, 5, 1, 9, 61, 1, 19, 13, 59, 1, 5, 1, 39, 4, 21, 9, 71, 1, 7 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,5

LINKS

Colin Barker, Table of n, a(n) for n = 2..1000

EXAMPLE

a(6) = 5 because the distinct prime factors of 6 are [2,3] and 2 / (1/2+1/3) = 12/5.

PROG

(PARI)

harmonicmean(v) = #v / sum(k=1, #v, 1/v[k])

a(n) = denominator(harmonicmean(factorint(n)~[1, ]))

vector(100, n, a(n+1))

CROSSREFS

Cf. A250096.

Sequence in context: A284252 A284254 A309206 * A028235 A028236 A066504

Adjacent sequences:  A250094 A250095 A250096 * A250098 A250099 A250100

KEYWORD

nonn

AUTHOR

Colin Barker, Nov 12 2014

STATUS

approved

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Last modified March 30 05:36 EDT 2020. Contains 333118 sequences. (Running on oeis4.)