A236443 -id:A236443 - cp's OEIS frontend

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

Abhiram R Devesh, Feb 08 2014

nonn

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.

			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.

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

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

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

A237017 Primes which start a Cunningham chain of length 4 where every entity of the chain is smallest of the prime number pair (p, p+8).

Original entry on oeis.org

359, 1069199, 1392269, 2614169, 10528649, 16981379, 18287309, 19463519, 21071489, 21171509, 22121579, 24857639, 40887569, 41809259, 76130129, 88362479, 118136279, 128893049, 131612609, 153318449, 289743689, 315495539

Offset: 1

Abhiram R Devesh, Feb 02 2014

nonn

a(n) generates a Cunningham chain of length 4 and a_n(i) + 8 is also prime for i = 1,2,3 and 4.

This sequence is infinite under Dickson's conjecture.

			a(1)=359, with associated Cunningham chain 359, 719, 1439, 2879; all of which are the lower member of a pair (p, p+8): (359,367), (719,727), (1439,1447), (2879,2887).

Chris K. Caldwell, Cunningham chain

Cf. A236443, A178421, A005602, A059763.

from sympy import isprime, primerange
is_a237017 = lambda p: all(isprime(q) for q in (p+8, 2*p+1, 2*p+9, 4*p+3, 4*p+11, 8*p+7, 8*p+15))
print(*[p for p in primerange(10**7) if is_a237017(p)], sep=', ')
# David Radcliffe, May 11 2025

cp's OEIS Frontend

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.

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