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A128646
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a(n) = denominator(Sum_{k=1..n} 1/(prime(k)-1)).
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8
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1, 2, 4, 12, 60, 10, 80, 720, 7920, 55440, 55440, 18480, 18480, 18480, 425040, 5525520, 160240080, 53413360, 160240080, 160240080, 480720240, 480720240, 19709529840, 19709529840, 39419059680, 197095298400, 3350620072800
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OFFSET
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1,2
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COMMENTS
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A120271(n) = numerator(Sum_{k=1..n} 1/(prime(k)-1)); A128648(n) = denominator(Sum_{k=1..n} (-1)^(k+1)/(prime(k)-1)); numbers m such that a(m) = A128648(m) are listed in A128649.
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LINKS
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FORMULA
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a(n) = denominator(Sum_{k=1..n} 1/(prime(k)-1)).
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MATHEMATICA
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Table[Denominator[Sum[1/(Prime[k]-1), {k, 1, n}]], {n, 1, 36}]
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CROSSREFS
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Cf. A120271 (numerator(Sum_{k=1..n} 1/(prime(k)-1))).
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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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