OFFSET
1,1
COMMENTS
Half the difference between consecutive primes is prime.
(1/2)(29 - 23) = 3, the 4th entry in the table.
MATHEMATICA
Select[Differences[Prime[Range[250]]]/2, PrimeQ] (* Harvey P. Dale, Dec 20 2012 *)
PROG
(PARI) f(n) = for(x=1, n, y=prime(x+1)-prime(x); if(isprime(y\2), print1(y\2", ")))
(Magma) [ a: n in [1..2500] | IsPrime(a) where a is ((NthPrime(n+1)-NthPrime(n)) div 2 )]; // Vincenzo Librandi, Apr 19 2011
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Cino Hilliard, Sep 09 2004
STATUS
approved