A368691 - OEIS

%I #9 Jan 12 2024 22:47:12

%S 3,23,31,73,83,157,167,211,251,353,373,443,467,503,509,523,541,571,

%T 647,727,751,941,947,977,1033,1069,1123,1201,1259,1361,1381,1493,1511,

%U 1531,1553,1613,1759,1811,2011,2207,2333,2351,2383,2399,2417,2543,2777,2927,3061,3067,3083,3301,3331,3511

%N Primes p such that p + 4 * q is prime, where q is the next prime after p.

%H Robert Israel, <a href="/A368691/b368691.txt">Table of n, a(n) for n = 1..10000</a>

%e a(3) = 31 is a term because 31 is prime, the next prime is 37, and 31 + 4 * 37 = 179 is prime.

%p filter:= proc(p) local q;

%p   if not isprime(p) then return false fi;

%p   q:= nextprime(p);

%p   isprime(p+4*q)

%p end proc:

%p select(filter, [seq(i,i=3..10000,2)]);

%t f[p_] := Module[{q}, If[!PrimeQ[p], Return[False]]; q = NextPrime[p]; PrimeQ[p + 4*q]];Select[Range[3,3511, 2],f] (* _James C. McMahon_, Jan 03 2024 *)

%Y Cf. A175914.

%K nonn

%O 1,1

%A _Zak Seidov_ and _Robert Israel_, Jan 03 2024