OFFSET
1,1
COMMENTS
The next term, a(11), has 84 digits. - Harvey P. Dale, Jul 24 2011
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..17
F. Firoozbakht, M. F. Hasler, Variations on Euclid's formula for Perfect Numbers, JIS 13 (2010) #10.3.1
Henri & Renaud Lifchitz, PRP Records
OpenPFGW Project, Primality Tester
FORMULA
a(n) = 3^A058959(n) - 4. - M. F. Hasler, Oct 31 2009
EXAMPLE
a(1) = 3^2 - 4 = 5 is the smallest prime of that form. - M. F. Hasler, Oct 31 2009
MATHEMATICA
Select[3^Range[200]-4, PrimeQ] (* Harvey P. Dale, Jul 24 2011 *)
PROG
(PARI) for( k=2, 999, is/*pseudo*/prime( p=3^k-4 ) & print1(p", ")) \\ M. F. Hasler, Oct 31 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Feb 10 2009
EXTENSIONS
a(5) corrected by M. F. Hasler, Oct 31 2009
a(10) from Harvey P. Dale, Jul 24 2011
STATUS
approved