OFFSET
1,2
COMMENTS
Except for the first term all terms are of the form 6m+2 or 6m+4. There are no further terms up to 34500. - Farideh Firoozbakht, Jul 17 2005
a(13) > 2*10^5. - Robert Price, Feb 05 2014
MATHEMATICA
Do[ If[ PrimeQ[ 3^n - n ], Print[ n ] ], {n, 0, 3000} ]
PROG
(PARI) for(k=1, 10^6, if(ispseudoprime(3^k-k), print1(k, ", "))); /* Joerg Arndt, Apr 07 2013 */
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert G. Wilson v, Nov 16 2000
EXTENSIONS
a(12) from Farideh Firoozbakht, Jul 17 2005
a(13) from Nico Puada, Sep 18 2023
STATUS
approved