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Search: id:A054415
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| A054415 |
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Smallest prime factor of n!-1. |
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+0
6
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| 1, 5, 23, 7, 719, 5039, 23, 11, 29, 13, 479001599, 1733, 87178291199, 17, 3041, 19, 59, 653, 124769, 23, 109, 51871, 625793187653, 149, 20431, 29, 239, 31, 265252859812191058636308479999999, 787
(list; graph; listen)
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OFFSET
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2,2
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LINKS
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Hisanori Mishima, Factorizations of many number sequences
Hisanori Mishima, Factorizations of many number sequences
R. G. Wilson v, Explicit factorizations
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EXAMPLE
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a(3)=5 because 3!-1=5 which is prime; a(5)=7 because 5!-1=119=7*17 and 7<17
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MATHEMATICA
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Do[ Print[ FactorInteger[ n! - 1, FactorComplete -> True][ [1, 1] ] ], {n, 3, 32} ]
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CROSSREFS
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Cf. A002582, A033312, A051301.
Sequence in context: A005632 A002069 A120488 this_sequence A156328 A078190 A081319
Adjacent sequences: A054412 A054413 A054414 this_sequence A054416 A054417 A054418
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KEYWORD
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nonn
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AUTHOR
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Henry Bottomley (se16(AT)btinternet.com), May 10 2000
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 01 2000
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