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A063898 Smallest k > 0 such that k + F_n are all primes, where F_n is the n-th Fermat number. 0
2, 2, 2, 14, 14, 14, 66746, 475424, 12124166, 14899339904 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Is this sequence finite?

LINKS

Table of n, a(n) for n=0..9.

EXAMPLE

For j=3 a(3)=2 because 257+2, 17+2, 5+2, 3+2 are all primes.

For j=4 a(4)=14 because 65537+14, 257+14, 17+14, 5+14, 3+14 are all primes.

PROG

(PARI) okprimep(mink, vecf) = {for (i=1, #vecf, if (! isprime(mink + vecf[i]), return (0)); ); return (1); }

a(n) = {mink = 1; vecf = vector(n+1, i, 2^(2^(i-1)) + 1); while (! okprimep(mink, vecf), mink++); mink; } \\ Michel Marcus, Sep 28 2013

CROSSREFS

Cf. A000215 (Fermat numbers).

Sequence in context: A049148 A183584 A289068 * A074052 A129409 A025521

Adjacent sequences:  A063895 A063896 A063897 * A063899 A063900 A063901

KEYWORD

hard,more,nonn

AUTHOR

Felice Russo, Aug 29 2001

EXTENSIONS

a(10) from Donovan Johnson, Oct 12 2008

STATUS

approved

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Last modified April 17 02:26 EDT 2021. Contains 343059 sequences. (Running on oeis4.)