OFFSET
1,1
COMMENTS
Except for 2, this is a subsequence of primes of the form 4k+1 (A002144). - Davide Rotondo, Oct 07 2024
EXAMPLE
2 is a term because 2 is prime and 2-1 = 1 equals the empty product.
5 is a term because 5 is prime, 5-1 = 2*2 = (3-1)*(3-1), and 3 is prime.
3329 is a term because 3329 is prime, 3329-1 = 4*16*52 = (5-1)*(17-1)*(53-1), and 5, 17, and 53 are prime. (This is the first term that requires more than two factors.)
CROSSREFS
KEYWORD
nonn,changed
AUTHOR
Pontus von Brömssen, Jun 19 2023
STATUS
approved