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 A289494 #19 Dec 30 2024 14:33:23
%S A289494 1,1,1,1,2,2,1,2,2,2,3,4,3,3,3,3,4,4,5,5,5,5,5,4,4,6,6,6,7,6,6,7,7,6,
%T A289494 7,6,5,6,6,7,8,9,8,8,9,9,8,9,10,11,10,10,10,10,9,9,10,10,11,11,11,11,
%U A289494 12,11,11,11,10,12,12,13,14,14,14,15,14
%N A289494 Number of primes in the interval [3n, 4n].
%H A289494 FUNG Cheok Yin, <a href="/A289494/b289494.txt">Table of n, a(n) for n = 1..10000</a>
%H A289494 Andy Loo, <a href="http://arxiv.org/abs/1110.2377">On the Primes in the Interval [3n, 4n]</a>, arXiv:1110.2377 [math.NT], 2011.
%t A289494 Join[{1},Rest[Table[PrimePi[4n]-PrimePi[3n],{n,80}]]] (* _Harvey P. Dale_, Dec 30 2024 *)
%Y A289494 Cf. A035250, A289493, A289495, A289496, A289497, A289498, A289499, A289500.
%K A289494 nonn,easy
%O A289494 1,5
%A A289494 _FUNG Cheok Yin_, Jul 07 2017