OFFSET
1,2
LINKS
C. Rivera (Ed.), Puzzle 482: Two Bergot questions, March 2009.
EXAMPLE
a(1)=0 since prime(1) = 2 cannot be written as pq-(p+q) for primes p,q.
a(2)=2 since prime(2) = 3 = 2*5-(2+5) = 3*3-(3+3) are the two possibilities.
PROG
(PARI) A157188(n)={ local(c=0, L=sqrtint(n=prime(n)+1)); fordiv( n, d, d>L&break; isprime(d+1) | next; isprime(n/d+1) & c++); c}
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Mar 11 2009
STATUS
approved