OFFSET
1,2
COMMENTS
a(55) > 2*10^5. - Robert Price, Mar 16 2014
All terms are verified primes (i.e., not probable primes). - Robert Price, Mar 16 2014
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
H. C. Williams and C. R. Zarnke, Some prime numbers of the forms 2*3^n+1 and 2*3^n-1, Math. Comp., 26 (1972), 995-998.
MATHEMATICA
Do[ If[ PrimeQ[ 10*3^n - 1], Print[n] ], {n, 1, 12901} ]
PROG
(PARI) v=[ ]; for(n=1, 1900, if(isprime(10*3^n-1), v=concat(v, n), )); v
CROSSREFS
KEYWORD
hard,nonn,changed
AUTHOR
EXTENSIONS
More terms from Robert G. Wilson v, Feb 05 2001
a(42)-a(54) from Robert Price, Mar 16 2014
a(55) from Riley Fisher, Aug 19 2024
Missing a(55) inserted by Riley Fisher, Oct 26 2024
STATUS
approved