A145477 - OEIS

%I #17 Jan 26 2024 12:43:43

%S 3,11,23,59,71,83,179,191,239,251,311,359,431,443,479,491,503,563,599,

%T 683,743,839,863,911,983,1019,1091,1103,1151,1163,1259,1283,1499,1523,

%U 1571,1619,1871,1931,2003,2039,2099,2339,2351,2411,2423,2531,2543,2579

%N Primes p such that (23 + p)/2 is prime.

%C All these primes are congruent to 3 mod 4 and (with the exception of the first term) to 11 mod 12.

%H Ivan Neretin, <a href="/A145477/b145477.txt">Table of n, a(n) for n = 1..10000</a>

%t aa = {}; k = 23; Do[If[PrimeQ[(k + Prime[n])/2], AppendTo[aa, Prime[n]]], {n, 1, 500}];aa

%t Select[Prime[Range[400]],PrimeQ[(23+#)/2]&] (* _Harvey P. Dale_, Jan 26 2024 *)

%o (PARI) list(n)=my(t=1, p, i=1); while(i<n, p=prime(i); i=i+1; if(p>2&&prime((23+p)/2), print1(p, ", "))) \\ _Anders Hellström_, Jan 23 2017

%Y Cf. A092109, A145471-A145480.

%K nonn

%O 1,1

%A _Artur Jasinski_, Oct 11 2008