This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A289497 #12 Jul 08 2017 12:16:45 %S A289497 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 A289497 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 A289497 10,12,12,12,12,12,12,13,13,11,12,12,10,9,10,10 %N A289497 Number of primes in the interval [6n, 7n]. %H A289497 FUNG Cheok Yin, <a href="/A289497/b289497.txt">Table of n, a(n) for n = 1..10000</a> %o A289497 (PARI) a(n) = primepi(7*n) - primepi(6*n); \\ _Michel Marcus_, Jul 08 2017 %Y A289497 Cf. A035250, A289493, A289494, A289495, A289496, A289498, A289499, A289500. %K A289497 nonn,easy %O A289497 1,6 %A A289497 _FUNG Cheok Yin_, Jul 07 2017