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Search: id:A125683
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| A125683 |
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Numerator of Sum[ (-1)^(k+1) * 1/(k(k+1)), {k,1,n} ]. |
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3
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| 1, 1, 5, 11, 2, 79, 331, 479, 493, 5297, 2701, 69071, 70061, 69203, 55963, 471181, 158395, 8960447, 45108541, 44831407, 45083347, 1031626241, 518238043, 5160071143, 5180664331, 15484789693, 15537907043, 64166447971, 64357670431
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OFFSET
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1,3
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COMMENT
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Numbers n such that a(n) is prime are listed in A125684(n) = {3,4,5,6,7,8,10,13,14,18,21,22,26,27,28,32,33,35,51,54,58,67,76,89,100,...}. Corresponding prime a(n) are listed in A125685(n) = a[ A125684(n) ] = {5,11,2,79,331,479,5297,70061,69203,8960447,45083347,...}.
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FORMULA
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a(n) = numerator[ Sum[ (-1)^(k+1) * 1/(k(k+1)), {k,1,n} ].
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MATHEMATICA
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Table[Numerator[Sum[(-1)^(k+1)*1/(k(k+1)), {k, 1, n}]], {n, 1, 40}]
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CROSSREFS
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Cf. A125684, A125685.
Adjacent sequences: A125680 A125681 A125682 this_sequence A125684 A125685 A125686
Sequence in context: A067958 A087463 A111118 this_sequence A125685 A098147 A100298
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KEYWORD
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nonn
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AUTHOR
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Alexander Adamchuk (alex(AT)kolmogorov.com), Nov 30 2006
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