OFFSET
1,1
COMMENTS
If n is in the sequence, then so is k*n for all odd k. - Robert Israel, Jan 10 2018
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
FORMULA
a(n) seems to be asymptotic to c*n with c=5.8...
MAPLE
N:= 100:
R:= NULL:
count:= 0:
for n from 1 while count < N do
if igcd(2^n+1, combinat:-fibonacci(n)) > 1 then
count:= count+1;
R:= R, n
fi
od:
R; # Robert Israel, Jan 10 2018
MATHEMATICA
Select[Range[400], !CoprimeQ[2^# + 1, Fibonacci[#]] &] (* Amiram Eldar, May 20 2022 *)
PROG
(PARI) isok(n) = gcd(2^n+1, fibonacci(n)) != 1; \\ Michel Marcus, Jan 10 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Sep 07 2002
STATUS
approved