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A110056 Least prime that ends a complete Cunningham chain (of the first kind) of length n. 4
13, 7, 167, 4079, 47, 2879, 71850239, 2444789759, 21981381119, 13357981992959, 681004115066879, 1136001594224639, 16756459239477534719, 781558105952602767359 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
"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 Washington Bomfim, Oct 21 2009]
LINKS
Chris Caldwell's Prime Glossary, Cunn ingham chains.
EXAMPLE
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.
CROSSREFS
Cf. A110059 for Cunningham chains of the second kind.
Cf. A005602 [From Washington Bomfim, Oct 21 2009]
Sequence in context: A152142 A298085 A177427 * A159562 A249024 A076116
KEYWORD
nonn,hard
AUTHOR
Alexandre Wajnberg, Sep 04 2005
EXTENSIONS
Edited and extended by David Wasserman, Aug 08 2006
a(13) and a(14) from Washington Bomfim, Oct 21 2009
STATUS
approved

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Last modified April 21 13:26 EDT 2024. Contains 371870 sequences. (Running on oeis4.)