A057327 First member of a prime quadruple in a 2p-1 progression.

1531, 2131, 2311, 3061, 6211, 6841, 7411, 10321, 13681, 15391, 16651, 18121, 22531, 23011, 24391, 29671, 30781, 31771, 33301, 35311, 41491, 44371, 46411, 54601, 56311, 57991, 60331, 61381, 66601, 67651, 78031, 83431, 85381, 88741

Offset: 1

Author

Patrick De Geest, Aug 15 2000

Keywords

• nonn

Comments

Numbers n such that n remains prime through 3 iterations of function f(x) = 2x - 1.

Examples

			Quadruplets are (1531,3061,6121,12241), (2131,4261,8521,17041), ...
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000
• Index entries for sequences related to primes in arithmetic progressions

Crossrefs

Cf. (A005382 and A005383), A057326, A057328, A057329, A057330, A005603.

Programs

Mathematica

Select[Prime[Range[9000]],And@@PrimeQ[NestList[2#-1&,#,3]]&] (* Harvey P. Dale, May 27 2012 *)

Extensions

Offset changed by Andrew Howroyd, Aug 13 2024