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A334580
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Denominator of Sum_{k=1..n} (-1)^(k+1)/k^2.
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4
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1, 4, 36, 144, 3600, 1200, 58800, 235200, 6350400, 6350400, 768398400, 768398400, 129859329600, 129859329600, 129859329600, 519437318400, 150117385017600, 50039128339200, 18064125330451200, 3612825066090240, 3612825066090240, 3612825066090240, 1911184459961736960
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OFFSET
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1,2
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COMMENTS
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For n = 1 to n = 19, we have a(n) = A068589(n), but a(20) = 3612825066090240 <> A068589(20) = 18064125330451200.
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LINKS
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EXAMPLE
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The first few fractions are 1, 3/4, 31/36, 115/144, 3019/3600, 973/1200, 48877/58800, 191833/235200, 5257891/6350400, 5194387/6350400, ... = A119682/A334580.
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MAPLE
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b := proc(n) local k: add((-1)^(k + 1)/k^2, k = 1 .. n): end proc:
seq(denom(b(n)), n=1..30);
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PROG
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(PARI) a(n) = denominator(sum(k=1, n, (-1)^(k+1)/k^2)); \\ Michel Marcus, May 07 2020
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CROSSREFS
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KEYWORD
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nonn,frac
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AUTHOR
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STATUS
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approved
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