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Search: id:A157833
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| A157833 |
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Numbers n such that Sum[(-1)^k*(n-k)!,k = 0, n]+1 is prime. |
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+0
1
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| 2, 3, 5, 7, 15, 19, 41, 59, 61, 105, 661, 2653, 3069, 3943, 4053
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Note that when n is even, 3 divides the summation.
The sums corresponding to terms >= 661 are only probable primes. [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Mar 13 2009]
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EXAMPLE
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a(2)=((-1)^0)(2-0)!+((-1)^1)(2-1)!+((-1)^2)(2-2)!+1=2!-1!+0!+1= 3 (prime).
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CROSSREFS
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Sequence in context: A097799 A005629 A028304 this_sequence A151531 A079987 A085547
Adjacent sequences: A157830 A157831 A157832 this_sequence A157834 A157835 A157836
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KEYWORD
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nonn
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AUTHOR
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Kyle D. Balliet (kdballie(AT)bloomu.edu), Mar 07 2009
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EXTENSIONS
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a(7) - a(15) from Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Mar 13 2009
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