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A119787 Numerator of the product of n and the n-th alternating harmonic number, sum ((-1)^(k+1)/k, k=1..n). 4
1, 1, 5, 7, 47, 37, 319, 533, 1879, 1627, 20417, 18107, 263111, 237371, 261395, 95549, 1768477, 1632341, 33464927, 155685007, 166770367, 156188887, 3825136961, 3602044091, 19081066231, 18051406831, 57128792093, 54260455193 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

a(n) almost always equals A058313(n): the numerator of the n-th alternating harmonic number, Sum ((-1)^(k+1)/k, k=1..n) except n=15,28,75,77,104,... The ratio a(n)/A058313(n) for n=1..400 is given in A119788.

LINKS

Table of n, a(n) for n=1..28.

FORMULA

a(n) = numerator[Sum[(-1)^(k+1)*n/k, {k, 1, n}]].

MATHEMATICA

Numerator[Table[Sum[(-1)^(i+1)*n/i, {i, 1, n}], {n, 1, 50}]]

CROSSREFS

Cf. A058313.

Sequence in context: A075830 A058313 A120301 * A025530 A106114 A217039

Adjacent sequences:  A119784 A119785 A119786 * A119788 A119789 A119790

KEYWORD

frac,nonn

AUTHOR

Alexander Adamchuk, Jun 26 2006

STATUS

approved

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Last modified June 17 04:26 EDT 2019. Contains 324183 sequences. (Running on oeis4.)