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A262858
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Denominators of the Nielsen-Jacobsthal series leading to Euler's constant.
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4
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OFFSET
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1,1
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COMMENTS
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gamma = 1 - 1/12 - 43/420 - 20431/240240 - 2150797323119/36100888223400 - ..., see formula (36) in the reference below.
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LINKS
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FORMULA
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a(n) = n * Sum_{k = 2^n + 1 .. 2^(n + 1)} (-1)^(k + 1)/k.
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EXAMPLE
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Denominators of 1/12, 43/420, 20431/240240, 2150797323119/36100888223400, ...
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MATHEMATICA
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a[n_] := Denominator[n*Sum[(-1)^(k + 1)/k, {k, 2^n + 1, 2^(n + 1)}]]; Table[a[n], {n, 1, 8}]
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PROG
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(PARI) a(n) = denominator(n*sum(k=2^n + 1, 2^(n + 1), (-1)^(k + 1)/k));
(Magma) [Denominator(n*(&+[(-1)^(k+1)/k: k in [2^n+1..2^(n+1)]])): n in [1..6]]; // G. C. Greubel, Oct 28 2018
(GAP) List(List([1..6], n->n*Sum([2^n+1..2^(n+1)], k->(-1)^(k+1)/k)), DenominatorRat); # Muniru A Asiru, Oct 29 2018
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CROSSREFS
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Cf. A075266, A075267, A001620, A195189, A002657, A002790, A262235, A075266, A006953, A001067, A262856 (numerators of this series).
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KEYWORD
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frac,nonn
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AUTHOR
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STATUS
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approved
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