A090865 Primes p such that (p-1)/2 is prime if p == 3 (mod 4) or (p-1)/4 is prime if p == 1 (mod 4).

7, 11, 13, 23, 29, 47, 53, 59, 83, 107, 149, 167, 173, 179, 227, 263, 269, 293, 317, 347, 359, 383, 389, 467, 479, 503, 509, 557, 563, 587, 653, 719, 773, 797, 839, 863, 887, 983, 1019, 1109, 1187, 1229, 1283, 1307, 1319, 1367, 1439, 1487, 1493, 1523, 1619

Offset: 1

Author

Benoit Cloitre, Feb 12 2004

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 1..10000

Crossrefs

Subsequence of A058500.

Union of (A005385 \ {5}) and A090866.

Programs

Mathematica

Select[Prime[Range[256]], PrimeQ[(#-1)/(5-Mod[#, 4])]& ] (* Jean-François Alcover, Jul 16 2012 *)

PARI

forprime(p=1, 1619, if (((p%4==3) && isprime((p-1)/2)==1) || ((p%4==1) && isprime((p-1)/4)), print1(p, ", "))) \\ Jinyuan Wang, Feb 09 2019