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Search: id:A110056
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| A110056 |
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Least prime that ends a complete Cunningham chain (of the first kind) of length n. |
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+0
4
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| 13, 7, 167, 4079, 47, 2879, 71850239, 2444789759, 21981381119, 13357981992959, 681004115066879, 1136001594224639, 16756459239477534719, 781558105952602767359
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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"Complete" means that this chain is not part of a longer Cunningham chain of the first kind.
Next term is greater than 4*10^17.
A005602(13)-> 8181864863026139 -> ... -> a(13) = 16756459239477534719. [From W. Bomfim (webonfim(AT)bol.com.br), Oct 21 2009]
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LINKS
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Chris Caldwell's Prime Glossary, Cunn ingham chains.
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EXAMPLE
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41->83->167 is a Cunningham chain of the first kind. It is complete because neither (41-1)/2 nor 2*167+1 is prime. It is the first such chain of three primes, so a(3) = 167.
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CROSSREFS
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Cf. A005384, A005385, A007700, A023272, A023302, A023330, A059452, A057326, A059455, A059761, A059762, A059763, A059764, A074313.
Cf. A110059 for Cunningham chains of the second kind.
Cf. A005602 [From W. Bomfim (webonfim(AT)bol.com.br), Oct 21 2009]
Sequence in context: A061045 A095389 A152142 this_sequence A159562 A076116 A010216
Adjacent sequences: A110053 A110054 A110055 this_sequence A110057 A110058 A110059
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KEYWORD
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nonn,hard
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AUTHOR
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Alexandre Wajnberg (alexandre.wajnberg(AT)ulb.ac.be), Sep 04 2005
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EXTENSIONS
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Edited and extended by David Wasserman (dwasserm(AT)earthlink.net), Aug 08 2006
a(13) and a(14) from W. Bomfim (webonfim(AT)bol.com.br), Oct 21 2009
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