

A263875


a(n) = least positive k such that A263874(n) + 2^k is prime.


1



1, 2, 3, 4, 5, 8, 10, 20, 29, 955, 4583176, 9092392
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OFFSET

1,2


COMMENTS

A263874 gives where the records occur.


LINKS

Table of n, a(n) for n=1..12.
mersenneforum.org, Five or Bust  The Dual Sierpinski Problem


PROG

(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));


CROSSREFS

Cf. A067760, A263874.
Sequence in context: A222297 A211981 A019997 * A125157 A093327 A186041
Adjacent sequences: A263872 A263873 A263874 * A263876 A263877 A263878


KEYWORD

nonn,hard,more


AUTHOR

Arkadiusz Wesolowski, Oct 28 2015


STATUS

approved



