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%I #12 Nov 22 2015 15:23:24
%S 1,2,3,4,5,8,10,20,29,955,4583176,9092392
%N a(n) = least positive k such that A263874(n) + 2^k is prime.
%C A263874 gives where the records occur.
%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(k, ", "); a=k+1));
%Y Cf. A067760, A263874.
%K nonn,hard,more
%O 1,2
%A _Arkadiusz Wesolowski_, Oct 28 2015