A109946 Smallest prime starting a complete two iterations Cunningham chain of the first and second kind.

2, 19, 41, 79, 331, 439, 499, 619, 829, 1031, 1069, 1279, 1451, 1481, 1511, 1811, 1889, 1901, 1931, 2089, 2179, 2791, 3019, 3109, 3181, 3449, 3491, 3769, 3821, 3911, 4159, 4231, 4639, 4861, 4951, 5081, 5419, 5441, 5749, 5849, 6101, 6131, 6709, 7151, 7349

Offset

1,1

Comments

Intersection of A057326 and A059762. The terms have to start a chain through iteration by either <2p+1> or <2p-1> operator (not mixed in the same chain); and the chains has to be three primes long.

Links

Table of n, a(n) for n=1..45.

Chris Caldwell, The Prime Glossary, Cunningham chains.

Example

a(1)=2 is here because 2 -> 3 -> 5 through <2p-1> and the chain ends here (with this operator).
a(2)=19 is here because 19 -> 37 -> 73 through <2p-1>.
a(3)=41 is here because 41 -> 83 -> 167 through <2p+1>.
- 11 is not here because it is well followed by two terms, but doesn't start this sequence (2->5->11->23->47).
- 89 is not here because it starts a 6 terms chain.

Crossrefs

Cf. A057326, A059762.

Sequence in context: A018610 A075682 A062587 * A141067 A296251 A307554

Adjacent sequences: A109943 A109944 A109945 * A109947 A109948 A109949

Keyword

nonn

Author

Alexandre Wajnberg, Aug 31 2005

Extensions

Terms computed by Gilles Sadowski.

Status

approved