A167464 - OEIS

%I #8 Sep 08 2022 08:45:48

%S 5,7,13,19,31,37,43,47,53,59,61,67,73,79,83,89,97,103,107,109,113,127,

%T 131,137,139,151,157,163,173,179,181,191,193,197,199,211,223,227,229,

%U 241,257,271,277,283,307,311,313,331,337,349,359,367,373,379,383,389

%N Primes p such that 20*p+19 is composite.

%H Vincenzo Librandi, <a href="/A167464/b167464.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Prime[Range[500]], !PrimeQ[20 # + 19] &]

%t (* _Vincenzo Librandi_, Feb 15 2014 *)

%o (Magma) [p: p in PrimesUpTo(400) | not IsPrime(20*p+19)]; // _Vincenzo Librandi_, Feb 15 2014

%Y Cf. A157977.

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Nov 04 2009