OFFSET
0,1
EXAMPLE
n=1, 2^1=2. If 2,3,5 are subtracted from 2, then 0,-1 and -3 arise, of which -3 is a prime so a(1)=-3. n=11, 2048-p=q. At first p=29 gives the prime q=2029.
CROSSREFS
KEYWORD
sign
AUTHOR
Labos Elemer, Oct 19 2000
STATUS
approved