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A082688
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Denominator of Sum_{k=1..n} 1/(n+k).
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2
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2, 12, 60, 840, 2520, 27720, 360360, 144144, 2450448, 232792560, 232792560, 5354228880, 26771144400, 11473347600, 332727080400, 20629078984800, 20629078984800, 144403552893600, 5342931457063200, 5342931457063200
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OFFSET
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1,1
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LINKS
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FORMULA
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limit n ->infinity Sum_{k=1..n} 1/(n+k) = log(2).
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EXAMPLE
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1/2, 7/12, 37/60, 533/840, 1627/2520, 18107/27720, 237371/360360, ...
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MATHEMATICA
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Table[HarmonicNumber[2 n] - HarmonicNumber[n], {n, 20}] // Denominator (* Eric W. Weisstein, Dec 14 2017 *)
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PROG
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(PARI) a(n) = denominator(sum(k=1, n, 1/(n+k))); \\ Michel Marcus, Dec 14 2017
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CROSSREFS
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KEYWORD
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frac,nonn,easy
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AUTHOR
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STATUS
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approved
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