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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
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1, 8, 311, 40808, 12185065, 6287341056, 4738802232119, 5387114456064096, 8850391860017878609, 18339240151336533115830, 44718225006409477834272143, 173879507464360746581828003860
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Sum of all possible products of taking n-1 primes out of next n primes.
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MATHEMATICA
| a[n_] := Numerator[Sum[1/Prime[i], {i, n(n-1)/2+1, n(n+1)/2}]]
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CROSSREFS
| Sequence in context: A000842 A202559 A193812 * A079504 A057982 A041769
Adjacent sequences: A081977 A081978 A081979 * A081981 A081982 A081983
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KEYWORD
| nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 04 2003
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EXTENSIONS
| More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 08 2003
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