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

Author

Alexandre Wajnberg, Aug 31 2005

Keywords

• nonn

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.

Examples

			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.
		

Links

• Chris Caldwell, The Prime Glossary, Cunningham chains.

Crossrefs

Cf. A057326, A059762.

Extensions

Terms computed by Gilles Sadowski.