OFFSET
1,1
COMMENTS
The first 27 terms (halved) are given in Table 1 by Paszkiewicz and Rotkiewicz. - R. J. Mathar, Aug 22 2012
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..215 (terms below 10^12, calculated from the b-file at A005935; terms 1..68 from Jeppe Stig Nielsen)
Adam Paszkiewicz and Andrzej Rotkiewicz, On a Problem of H. J. A. Duprac, Tatra Mt. Math. Publ. 32 (2005) 15-32, MR2206908.
Eric Weisstein's World of Mathematics, Fermat Pseudoprime.
MATHEMATICA
Do[ f=PowerMod[ 3, 2n-1, 2n ]; If[ f==1, Print[ 2n ] ], {n, 2, 7000000} ]
PROG
(PARI) forstep(n=4, 10^10, 2, Mod(3, n)^(n-1)==1 && print1(n, ", ")) \\ Jeppe Stig Nielsen, Apr 25 2018
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, May 26 2007, Jun 17 2007
EXTENSIONS
More terms from Alexander Adamchuk, Jun 17 2007
a(25)-a(27) from Jeppe Stig Nielsen, Apr 25 2018
STATUS
approved