OFFSET
1,1
COMMENTS
More generally, if a and b are even numbers, let Seq(a,b) be the sequence of primes of the form p*(p+a)+b where p and p+a are primes. Seq(a,b) is finite if either a^2+b == 2 (mod 3) or a^2-4*b is a square. Is it infinite in all other cases?
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
MATHEMATICA
Select[ #(#+4)+2&/@Select[Prime/@Range[500], PrimeQ[ #+4]&], PrimeQ]
PROG
(PARI) prodtp(n1, n2, a, b)=local(f, x); f=0; forprime(x=n1, n2, if(isprime(x+a), f=x*(x+a)+b; if(isprime(f), print(x" "x+a" "f" "); ); ); ); \ Computes that part of Seq(a, b) with n1<=p<=n2.
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Cino Hilliard, Dec 08 2002
EXTENSIONS
Edited by Dean Hickerson, Dec 10 2002
STATUS
approved