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 A091267 #9 Sep 21 2012 18:25:47
%S A091267 1,2,2,1,2,1,2,2,2,2,1,1,2,1,1,4,1,1,1,1,1,2,1,1,2,2,1,1,2,7,1,1,1,1,
%T A091267 1,1,1,2,2,1,2,2,3,1,1,2,1,2,5,1,2,2,1,1,1,1,1,2,1,1,1,2,1,1,1,1,2,1,
%U A091267 3,1,1,1,2,3,2,2,5,5,1,1,1,2,1,1,1,1,2,4,2,1,1,1,1,2,3,1,1,1,2,2,1,1,3,4,1
%N A091267 Lengths of runs of 3's in A039702.
%C A091267 Number of primes congruent to 3 mod 4 in sequence before interruption by a prime 1 mod 4.
%D A091267 Enoch Haga, Exploring prime numbers on your PC and the Internet with directions to prime number sites on the Internet, 2001, pages 30-31. ISBN 1-885794-17-7.
%H A091267 T. D. Noe, <a href="/A091267/b091267.txt">Table of n, a(n) for n = 1..10000</a>
%F A091267 Count primes congruent to 3 mod 4 in sequence before interruption by a prime divided by 4 with remainder 1.
%e A091267 a(16)=4 because this is the sequence of primes congruent to 3 mod 4: 199, 211, 223, 227. The next prime is 229, a prime 1 mod 4.
%t A091267 t = Length /@ Split[Table[Mod[Prime[n], 4], {n, 2, 400}]]; Most[Transpose[Partition[t, 2]][[1]]] (* _T. D. Noe_, Sep 21 2012 *)
%Y A091267 Cf. A002144, A002145, A091318, A039702, A091237.
%K A091267 easy,nonn
%O A091267 1,2
%A A091267 _Enoch Haga_, Feb 22 2004