OFFSET
1,1
COMMENTS
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..150
Jonathan Vos Post, Sums of three Mersenne primes, and prime sums of three Mersenne primes, SeqFan list, Mar 5, 2010.
FORMULA
EXAMPLE
MATHEMATICA
Union[Mean/@Tuples[Select[2^Prime[Range[20]]-1, PrimeQ], {2}]] (* Harvey P. Dale, Mar 12 2011 *)
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Mar 06 2010
STATUS
approved