A237495 Primes which start a Cunningham chain of length 5 where every prime in the chain is the smaller of a pair of twin primes.

41887255409, 364223689829, 376655795669, 790031896499, 1558600513469, 2180283962009, 3266149150109, 4424063189699, 4655123392919, 6924093600269, 7706450161409, 9792446379869, 14825914106849, 15049625144399, 15612571518389, 18228407987789, 20440411077239

Offset

1,1

Comments

This is subset of the sequence A236443. Of the first 10000 terms in the sequence A236443 only 48 have length 5.

a(n) generates a Cunningham chain of length 5 and a_n(i) + 2 is also prime for i = 1,2,3,4 and 5.

This sequence is infinite under Dickson's conjecture.

Links

David Radcliffe, Table of n, a(n) for n = 1..284 (terms 1..48 from Abhiram R Devesh).

Chris Caldwell, Cunningham Chain

Example

a(1) = 41887255409, with associated Cunningham chain of length 5: 41887255409, 83774510819, 167549021639, 335098043279, 670196086559, each of which is the smaller of a pair of twin primes.

Prog

(C++) // See b-file.

Crossrefs

Cf. A178421, A005602, A236443 is a superset of this sequence.

Sequence in context: A172631 A172721 A259350 * A227387 A179227 A003940

Adjacent sequences: A237492 A237493 A237494 * A237496 A237497 A237498

Keyword

nonn

Author

Abhiram R Devesh, Feb 08 2014

Extensions

a(11)-a(17) from David Radcliffe, Aug 09 2025

Status

approved