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A109621
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Numbers n such that the numerator of sum_{k=0..n} 1/k!, in reduced form, is prime.
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0
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1, 2, 5, 9, 24, 32, 321, 343, 352, 511, 685, 807, 966, 1079, 1274, 1381, 2016, 3226
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OFFSET
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1,2
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COMMENTS
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Terms through 807 correspond to certified primes.
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LINKS
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Table of n, a(n) for n=1..18.
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EXAMPLE
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sum_{k=0..9} 1/k! = 98641/36288 and 98641 is prime, so 9 is in the sequence.
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MATHEMATICA
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s = 0; Do[s += 1/n!; k = Numerator[s]; If[PrimeQ[k], Print[n]], {n, 0, 3300}]
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CROSSREFS
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Sequence in context: A088356 A192477 A047044 * A075200 A075198 A006405
Adjacent sequences: A109618 A109619 A109620 * A109622 A109623 A109624
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KEYWORD
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hard,more,nonn
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AUTHOR
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Ryan Propper (rpropper(AT)stanford.edu), Aug 01 2005
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STATUS
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approved
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