OFFSET
1,2
COMMENTS
Also, numbers k such that 4^k == -1/2 (mod k) (cf. A296369). - Max Alekseyev, Sep 15 2018
If k is in the sequence, and m is another divisor of 2^(2*k+1)+1 and is coprime to k, then m*k is in the sequence. - Robert Israel, Sep 14 2018
MAPLE
filter:= n -> 2 &^ (2*n+1)+1 mod n = 0:
select(filter, [$1..10^7]); # Robert Israel, Sep 14 2018
PROG
(PARI) is_A319222(n) = Mod(2, n)^(2*n+1)==-1;
CROSSREFS
KEYWORD
nonn
AUTHOR
Altug Alkan, Sep 13 2018
STATUS
approved