OFFSET
0,1
COMMENTS
The first five terms of this sequence correspond to Fermat primes.
Note that 7072833120 is not the smallest base to give at least six possibly nonconsecutive k values. For example, 292582836^(2^k) + 1 is prime for k = 0,1,2,3,4,7. - Jeppe Stig Nielsen, Sep 18 2022
LINKS
PrimeGrid, Generalized Fermat Progression Search
Carlos Rivera, Puzzle 137. Product of primes + 1, a square, The Prime Puzzles and Problems Connection.
Carlos Rivera, Prime Puzzle 399. Some more terms, The Prime Puzzles and Problems Connection.
EXAMPLE
a(5)=7072833120 because 7072833120^2^k+1 for k=0,1,2,3,4,5 are primes.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Farideh Firoozbakht, Jan 31 2004
EXTENSIONS
a(6) from Jens Kruse Andersen, May 06 2007
a(7) from Kellen Shenton, Aug 13 2020
STATUS
approved