OFFSET
1,1
COMMENTS
10th term has 150 digits. - Emeric Deutsch, Mar 07 2009
Primes of the form 1 + A028361(k), any k > 0. - R. J. Mathar, Jul 10 2011
EXAMPLE
(2^0 + 1)*(2^1 + 1)*(2^2 + 1)*(2^3 + 1)*(2^4 + 1) + 1 = 2*3*5*9*17 + 1 = 4591.
MAPLE
a := proc (n) if isprime(1+product(2^k+1, k = 0 .. n)) = true then 1+product(2^k+1, k = 0 .. n) else end if end proc: seq(a(n), n = 0 .. 40); # Emeric Deutsch, Mar 07 2009
MATHEMATICA
Select[Table[Product[2^j+1, {j, 0, k}], {k, 0, 30}]+1, PrimeQ] (* Harvey P. Dale, Aug 01 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot, Feb 17 2009
EXTENSIONS
a(9) from Emeric Deutsch, Mar 07 2009
STATUS
approved