A090865 - OEIS

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

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OFFSET

1,1

LINKS

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

MATHEMATICA

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

PROG

(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

CROSSREFS

Subsequence of A058500.

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