login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

Integers for which the smallest k in A067760 such that n + 2^k is prime increases.
3

%I #11 Nov 22 2015 15:23:13

%S 1,7,23,31,47,61,139,271,287,773,2131,40291

%N Integers for which the smallest k in A067760 such that n + 2^k is prime increases.

%H mersenneforum.org, <a href="http://www.mersenneforum.org/forumdisplay.php?f=86">Five or Bust - The Dual Sierpinski Problem</a>

%o (PARI) a=1; forstep(n=1, 773, 2, k=1; while(!ispseudoprime(n+2^k), k++); if(k+1>a, print1(n, ", "); a=k+1));

%Y Cf. A067760, A123252.

%Y A263875 gives the record values.

%K nonn,hard,more

%O 1,2

%A _Arkadiusz Wesolowski_, Oct 28 2015