Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #16 May 14 2023 04:14:21
%S 1,1,4,0,1,4,1,0,8,4,1,5,2,0,4,7,1,3,2,2,6,1,1,5,2,6,5,3,1,1,0,1,4,6,
%T 1,4,1,4,9,5,7,0,0,2,2,5,1,3,0,8,4,1,5,2,18,0,9,3,1,1,9,2,4,5,3,2,6,5,
%U 4,9,3,4,11,1,1,3,4,20,0,8,2,4,3,3,15,6
%N The number of primes between two consecutive lucky primes, bounds excluded.
%H Amiram Eldar, <a href="/A309333/b309333.txt">Table of n, a(n) for n = 1..10000</a>
%e a(1): Between the first two lucky primes (3, 7) there is one prime (5).
%e a(3): Between 13 and 31 there are 4 primes (17, 19, 23, 29).
%o (SageMath)
%o def count_primes_between(a, b):
%o return len(prime_range(a+1, b))
%o [count_primes_between(A031157[i], A031157[i+1]) for i in range (len(A031157[0:20])-1)]
%Y Cf. A000959, A031157, A309334, A176559.
%K nonn
%O 1,3
%A _Hauke Löffler_, Jul 24 2019