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A120296
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Numerator of Sum_{k=1..n} (-1)^(k+1)/k^4.
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20
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1, 15, 1231, 19615, 12280111, 4090037, 9824498837, 157151464517, 38193952437631, 7637983935923, 111835788321880643, 111830093529238643, 3194097388508809394723, 3194009594644356242723, 15970381078317764649391
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OFFSET
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1,2
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COMMENTS
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p divides a(p-1) for prime p > 2 - similar to Wolstenholme's theorem for A007406(n) (= numerator of Sum_{k=1..n} 1/k^2) and for A007410(n) (= numerator of Sum_{k=1..n} 1/k^4).
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LINKS
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FORMULA
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a(n) = numerator(Sum_{k=1..n} (-1)^(k+1)/k^4).
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EXAMPLE
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The first few fractions are 1, 15/16, 1231/1296, 19615/20736, 12280111/12960000, 4090037/4320000, 9824498837/10372320000, ... = A120296/A334585. - Petros Hadjicostas, May 06 2020
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MATHEMATICA
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Numerator[Table[Sum[(-1)^(k+1)/k^4, {k, 1, n}], {n, 1, 20}]]
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PROG
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(PARI) a(n) = numerator(sum(k=1, n, (-1)^(k+1)/k^4)); \\ 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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EXTENSIONS
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STATUS
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approved
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