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Search: id:A119787
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| A119787 |
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Numerator of the product of n and the n-th alternating harmonic number, sum ((-1)^(k+1)/k, k=1..n). |
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+0
5
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| 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
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OFFSET
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1,3
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COMMENT
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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.
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FORMULA
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a(n) = numerator[Sum[(-1)^(k+1)*n/k, {k, 1, n}]].
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MATHEMATICA
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Numerator[Table[Sum[(-1)^(i+1)*n/i, {i, 1, n}], {n, 1, 50}]]
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CROSSREFS
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Cf. A058313.
Adjacent sequences: A119784 A119785 A119786 this_sequence A119788 A119789 A119790
Sequence in context: A075830 A058313 A120301 this_sequence A025530 A106114 A110420
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KEYWORD
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frac,nonn
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AUTHOR
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Alexander Adamchuk (alex(AT)kolmogorov.com), Jun 26 2006
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