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Search: id:A006794
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| A006794 |
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Primes p such that -1 + product of primes up to p is prime.
(Formerly M2474)
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+0
18
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| 3, 5, 11, 13, 41, 89, 317, 337, 991, 1873, 2053, 2377, 4093, 4297, 4583, 6569, 13033, 15877
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Or, p such that primorial(p) - 1 is prime.
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
C. K. Caldwell, On The Primality of n!+- 1 and 2\cdot 3 \cdot 5\cdots p+- 1, Math. Comput. 64, 889-890, 1995.
C. K. Caldwell and Y. Gallot, On the primality of n!+-1 and 2*3*5*...*p+-1, Math. Comp., 71 (2001), 441-448.
H. Dubner, Factorial and primorial primes, J. Rec. Math., 19 (No. 3, 1987), 197-203.
R. K. Guy, Unsolved Problems in Number Theory, Section A2.
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LINKS
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C. K. Caldwell, Primorial Primes
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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CROSSREFS
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A057704 gives same sequence in a different way. A057705 gives the actual primes. Cf. A002110, A005234, A014545, A018239.
Sequence in context: A105071 A089251 A147568 this_sequence A032457 A122564 A162876
Adjacent sequences: A006791 A006792 A006793 this_sequence A006795 A006796 A006797
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KEYWORD
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nonn,hard,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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Stated incorrectly in CRC Standard Mathematical Tables and Formulae, 30th ed., 1996, p. 101; corrected in 2nd printing.
Corrected by Arlin Anderson (starship1(AT)gmail.com), who reports that he and Don Robinson have checked this sequence through about 63000 digits without finding another term (Jul 04 2000).
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