OFFSET
1,1
COMMENTS
Then n - 1 and n + 1 are almost always a pair of twin primes, and the set of these should be an infinite subset of all twin primes.
If n - 1 and n + 1 are simultaneously composite, this occurs very rarely.
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Reikku Kulon, Jul 15 2009
STATUS
approved