OFFSET
1,2
COMMENTS
Starting with a(2)=2, numbers m such that 10(m-1)+{1,3,7,9} are all primes.
Essentially the same as A064975. [From R. J. Mathar, Aug 11 2008]
REFERENCES
4 is maximal possible number of primes between 10n and 10(n+1).
EXAMPLE
11 is OK because 10(11-1)+{1,3,7,9} = 101,103,107,109 all prime.
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Mar 01 2006
STATUS
approved