A110056 Least prime that ends a complete Cunningham chain (of the first kind) of length n.

13, 7, 167, 4079, 47, 2879, 71850239, 2444789759, 21981381119, 13357981992959, 681004115066879, 1136001594224639, 16756459239477534719, 781558105952602767359

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

Table of n, a(n) for n=1..14.

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. 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 Washington Bomfim, Oct 21 2009]

Sequence in context: A152142 A298085 A177427 * A159562 A249024 A076116

Adjacent sequences: A110053 A110054 A110055 * A110057 A110058 A110059

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