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A119788 Ratio of the numerator of the product of n and the n-th alternating harmonic number n*H'(n) to the numerator of the n-th alternating harmonic number H'(n) = Sum_{k=1..n} (-1)^(k+1)*1/k. 4
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 5, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 7, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 5, 1, 11, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 13 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,15
COMMENTS
Indices n such that a(n) is not equal to 1 are listed in A121594.
It appears that most a(n) > 1 are a prime divisor of their corresponding indices A121594(n). The first and only composite term up to a(6000) is a(1470) = 49 that also divides its index.
A compressed version of this sequence (all 1 entries are excluded) is A121595.
LINKS
FORMULA
a(n) = numerator(n*Sum_{i=1..n} (-1)^(i+1)*1/i) / numerator(Sum_{i=1..n}(-1)^(i+1)*1/i).
a(n) = A119787(n) / A058313(n).
MATHEMATICA
Numerator[Table[n*Sum[(-1)^(i+1)*1/i, {i, 1, n}], {n, 1, 600}]]/Numerator[Table[Sum[(-1)^(i+1)*1/i, {i, 1, n}], {n, 1, 600}]]
CROSSREFS
Sequence in context: A257098 A322356 A337337 * A334561 A059592 A295554
KEYWORD
frac,nonn
AUTHOR
Alexander Adamchuk, Jun 26 2006, Sep 21 2006
STATUS
approved

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Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)