A098013 - OEIS

%I #13 Jan 31 2020 13:39:06

%S 4,4,4,6,6,4,4,6,6,6,4,6,4,6,4,4,4,14,4,6,10,6,6,4,6,6,10,4,4,4,6,10,

%T 6,6,6,6,4,10,14,4,4,14,6,10,4,6,6,6,4,6,4,10,10,6,4,6,4,4,4,4,6,6,10,

%U 6,6,6,10,6,6,6,6,4,10,4,6,6,4,6,10,10,6,6,4,6,4,4,14,10,10,4,10,14,4,4,14

%N Differences between consecutive primes that are twice primes.

%C 11 - 7 = 4 = double 2, the first entry in the table.

%H Robert Israel, <a href="/A098013/b098013.txt">Table of n, a(n) for n = 1..10000</a>

%p R:= NULL: count:= 0:

%p q:= 2: p:= 3:

%p while count < 100 do

%p   q:= p; p:= nextprime(p);

%p   if isprime((p-q)/2) then

%p      count:= count+1; R:= R, p-q

%p   fi

%p od:

%p R; # _Robert Israel_, Jun 05 2018

%t Select[Differences[Prime[Range[500]]],PrimeQ[#/2]&] (* _Harvey P. Dale_, Jan 31 2020 *)

%o (PARI) f(n) = for(x=1,n,y=prime(x+1)-prime(x);if(isprime(y\2),print1(y",")))

%Y Cf. A100484 (twice primes).

%K easy,nonn

%O 1,1

%A _Cino Hilliard_, Sep 09 2004