OFFSET
1,2
COMMENTS
These seem to be much rarer than the corresponding even numbers.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..51
PROG
(PARI) is(n)=n%2 && Mod(2, 2*n-1)^n==1
CROSSREFS
KEYWORD
nonn
AUTHOR
Charles R Greathouse IV, Dec 09 2013
STATUS
approved