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Search: id:A109616
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| A109616 |
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Numbers n such that (10's complement factorial of n) + 1 is prime. |
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+0
2
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| 2, 5, 10, 25, 36, 44, 65, 67, 138, 149, 176, 212, 279, 1293, 2367, 2463, 2707, 3130, 4150, 4635
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Larger values not certified.
Some of the larger entries may only correspond to probable primes.
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EXAMPLE
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a(2)=5 because (10-5)*(10-4)*(10-3)*(10-2)*(10-1) + 1 = 15121 is prime.
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MATHEMATICA
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f[n_] := 10^Length[IntegerDigits[n]] - n; p = 1; Do[p *= f[n]; If[PrimeQ[p + 1], Print[n]], {n, 4635}] - Ryan Propper (rpropper(AT)stanford.edu), May 20 2006
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CROSSREFS
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Cf. A110396.
Adjacent sequences: A109613 A109614 A109615 this_sequence A109617 A109618 A109619
Sequence in context: A106376 A001431 A054866 this_sequence A018262 A018356 A026383
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KEYWORD
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more,nonn
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AUTHOR
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Jason Earls (jcearls(AT)cableone.net), Aug 01 2005
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EXTENSIONS
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More terms from Ryan Propper (rpropper(AT)stanford.edu), May 20 2006
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