%I #12 Jul 08 2017 12:16:45

%S 1,1,1,0,1,2,2,1,2,2,3,3,3,2,3,5,4,2,2,4,4,4,4,5,5,6,5,5,6,5,5,5,5,5,

%T 7,7,8,7,7,7,8,8,7,7,8,8,6,6,6,8,9,8,7,8,10,10,10,10,9,9,10,11,11,10,

%U 10,12,12,12,12,12,12,13,13,11,12,12,10,9,10,10

%N Number of primes in the interval [6n, 7n].

%H FUNG Cheok Yin, <a href="/A289497/b289497.txt">Table of n, a(n) for n = 1..10000</a>

%o (PARI) a(n) = primepi(7*n) - primepi(6*n); \\ _Michel Marcus_, Jul 08 2017

%Y Cf. A035250, A289493, A289494, A289495, A289496, A289498, A289499, A289500.

%K nonn,easy

%O 1,6

%A _FUNG Cheok Yin_, Jul 07 2017