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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified November 24 20:34 EST 2020. Contains 338616 sequences. (Running on oeis4.)