OFFSET
1,2
COMMENTS
The next terms are > 12000. - Bruno Berselli, Sep 30 2012
a(8) exceeds 120,000 (from Mischa Rodermond). - Jeppe Stig Nielsen, Dec 05 2022
LINKS
Henri Lifchitz and Renaud Lifchitz, PRP Top: Search for 6^k+k, finds a(7).
MATHEMATICA
Do[ If[ PrimeQ[6^n + n], Print[n] ], {n, 2500} ]
Select[Range[0, 4000], PrimeQ[(6^# + #)] &] (* Vincenzo Librandi, Sep 29 2012 *)
PROG
(PARI) is(n)=ispseudoprime(6^n+n) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jan 04 2001
EXTENSIONS
a(5) from Vincenzo Librandi, Sep 29 2012
a(6) from Bruno Berselli, Sep 29 2012
a(7) from Jeppe Stig Nielsen, Dec 05 2022
STATUS
approved