

A280003


Numbers k such that 7*2^k + 1 is a prime factor of a Fermat number 2^(2^m) + 1 for some m.


3




OFFSET

1,1


COMMENTS

18233956 belongs to this sequence, but its position is currently unknown.  Jeppe Stig Nielsen, Oct 05 2020


LINKS



PROG

(Magma) IsInteger := func<k  k eq Floor(k)>; [n: n in [1..320]  IsPrime(k) and IsInteger(Log(2, Modorder(2, k))) where k is 7*2^n+1];


CROSSREFS



KEYWORD

nonn,hard,more


AUTHOR



STATUS

approved



