OFFSET
1,1
COMMENTS
The first 0 is for n=52. Are there others?
EXAMPLE
2+2*3-1 = 7 so a(1) = 2.
2*3+2*3*5-1 = 35 is composite but 2*3+2*3*5+1 = 37 is prime so a(2) = 3.
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Mar 01 2007
STATUS
approved