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Search: id:A081980
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| A081980 |
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a(n) = numerator of the sum of the reciprocals of the n primes from prime(n(n-1)/2+1) to prime(n(n+1)/2). |
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+0
1
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| 1, 8, 311, 40808, 12185065, 6287341056, 4738802232119, 5387114456064096, 8850391860017878609, 18339240151336533115830, 44718225006409477834272143, 173879507464360746581828003860
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Sum of all possible products of taking n-1 primes out of next n primes.
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MATHEMATICA
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a[n_] := Numerator[Sum[1/Prime[i], {i, n(n-1)/2+1, n(n+1)/2}]]
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CROSSREFS
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Adjacent sequences: A081977 A081978 A081979 this_sequence A081981 A081982 A081983
Sequence in context: A034977 A065141 A000842 this_sequence A079504 A057982 A041769
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 04 2003
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EXTENSIONS
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More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 08 2003
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