OFFSET
1,5
COMMENTS
Conjecture: a(n) > 0 for n > 6.
Conjecture: With Sq=sum of q for n=1 to N and Sp=sum of p(n) for n=1 to N, lim sup Sq/Sp = 0.
LINKS
Pierre CAMI, Table of n, a(n) for n = 1..10000
EXAMPLE
No solution for n=1 to 4 prime(n) = 2, 3, 5, 7.
For prime(5)=11, 11^2-7^2-1 = 71, 71 and 73 twin primes so q(5)=7.
No solution for prime(6)=13
For prime(7)=17, 17^2-7^2-1=239, 239 and 241 twin primes so q(7)=7.
PROG
(PARI) a(n)=my(p=prime(n)); forprime(q=2, p-1, if(isprime(p^2-q^2-1)&&isprime(p^2-q^2+1), return(q))); 0 \\ Charles R Greathouse IV, Dec 27 2011
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Dec 27 2011
STATUS
approved