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A088258
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Factorials F which have at least one prime neighbor, i.e., F+1 or F-1 or both are primes.
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3
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1, 2, 6, 24, 720, 5040, 39916800, 479001600, 87178291200, 10888869450418352160768000000, 265252859812191058636308480000000, 263130836933693530167218012160000000
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OFFSET
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1,2
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COMMENTS
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Conjecture: sequence is infinite. But there are finitely many members which are sandwiched between twin primes.
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LINKS
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FORMULA
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EXAMPLE
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2 is in the sequence because 2 + 1 is prime.
6 is in the sequence because both 6 - 1 and 6 + 1 are prime.
24 is in the sequence because 24 - 1 is prime.
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MAPLE
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select(t -> isprime(t+1) or isprime(t-1), [seq(n!, n=1..100)]); # Robert Israel, Aug 25 2016
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MATHEMATICA
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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