%I #4 Mar 30 2012 18:40:00
%S 2,2,3,4,6,6,8,8,10,13,13,17,17,17,19,21,23,24,27,27,26,29,30,32,36,
%T 36,36,38,37,38,44,45,47,46,51,51,54,55,56,57,58,58,62,62,62,62,68,73,
%U 74,74,74,75,75,79,81,82,82,83,86,86,85,89,94,94,94,95,100,101,106,105,106
%N Number of primes between prime(n) and 3prime(n).
%e a(1)=2 because between p=2 and 6 there are exactly two primes, 3
%e and 5.
%t Table[ PrimePi[3Prime[n]] - n, {n, 70}]
%K easy,nonn
%O 1,1
%A _Giovanni Teofilatto_, Dec 25 2004
%E Corrected and extended by _Ray Chandler_, Dec 25, 2004