OFFSET
1,3
COMMENTS
The associated primes are in A007505.
FORMULA
a(n) = A002235(n+1)-1. - R. J. Mathar, Aug 17 2009
EXAMPLE
n=0 is in the sequence because 6*2^0-1=5 is prime. n=1 is in the sequence because 6*2^1-1=11 is prime.
PROG
(PARI) is(n)=ispseudoprime(6*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Aug 15 2009
EXTENSIONS
Extended by R. J. Mathar, Aug 17 2009
a(28)-a(43) from Donovan Johnson, Jul 09 2010
STATUS
approved