A247101 Primes p such that 2*(p^2-1) - 1 and 2*(p^2-1) + 1 are also primes.

2, 11, 41, 59, 181, 379, 571, 659, 1429, 1439, 1721, 1879, 2029, 2239, 2351, 2381, 2579, 2671, 3209, 3581, 4159, 4229, 4271, 4969, 4999, 6299, 6451, 6551, 7349, 7841, 10391, 10399, 11059, 11551, 12841, 13049, 13159, 13619, 14071, 15329, 15581, 15889, 16811, 17231, 17749, 18719, 20219

Offset: 1

Author

Juri-Stepan Gerasimov, Nov 18 2014

Keywords

• nonn

Comments

Subsequence of prime terms of A249446.

Examples

			2 is in this sequence because 2, 2*(2^2-1) - 1 = 5 and 2*(2^2-1) + 1 = 7 are all primes.
		

Crossrefs

Cf. A249446.

Programs

Magma

[ n: n in [1..22000] | IsPrime(n) and IsPrime(2*(n^2-1)-1) and IsPrime(2*(n^2-1)+1) ];

Mathematica

Select[Range[25000], PrimeQ[#] && PrimeQ[2 #^2 - 3] && PrimeQ[2 #^2 - 1] &] (* Vincenzo Librandi, Nov 19 2014 *)