A108273 - OEIS

%I #13 Jan 17 2021 18:13:59

%S 37,53,277,65557,4503599627370517

%N Consider primes p and q such that p = 2^k + 21 and q = 2^(k+1) + 21 for some k; sequence gives values of q.

%t Select[Partition[2^Range[100]+21,2,1],AllTrue[#,PrimeQ]&][[All,2]] (* _Harvey P. Dale_, Jan 17 2021 *)

%o (PARI) g(m,n,b) = { for(x=0,n, y=m+b^x+b%2; z=m+b^(x+1)+b%2; if(isprime(y)&isprime(z),print1(y",") ) ) }

%Y Cf. A108272.

%K nonn

%O 1,1

%A _Cino Hilliard_, Jun 29 2005