The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

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