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 A267098 #8 Mar 07 2018 18:22:49
%S A267098 0,1,1,2,3,3,3,4,5,5,6,6,6,7,8,8,9,9,10,11,11,12,13,13,13,13,14,15,15,
%T A267098 15,16,17,17,18,18,19,19,20,21,21,22,22,23,23,23,24,25,26,27,27,27,28,
%U A267098 28,29,29,30,30,31,31,31,32,32,33,34,34,34,35,35,36,36,36,37,38,38,39,40,40,40,40,40,41,41,42
%N A267098 a(n) = number of 4k+3 primes among first n primes; least monotonic left inverse of A080148.
%C A267098 a(n) = number of 4k+3 primes (A002145) among primes in range 2 .. A000040(n).
%H A267098 Antti Karttunen, <a href="/A267098/b267098.txt">Table of n, a(n) for n = 1..65537</a>
%F A267098 Other identities. For all n >= 1:
%F A267098 a(A080148(n)) = n.
%F A267098 a(n) + A267097(n) = n-1.
%t A267098 Accumulate[Table[If[IntegerQ[(n-3)/4],1,0],{n,Prime[Range[90]]}]] (* _Harvey P. Dale_, Mar 07 2018 *)
%o A267098 (Scheme, with _Antti Karttunen_'s IntSeq-library)
%o A267098 (define A267098 (LEFTINV-LEASTMONO 1 1 A080148))
%Y A267098 Cf. A000040, A002145, A080148, A267097.
%Y A267098 Cf. also A267101.
%K A267098 nonn
%O A267098 1,4
%A A267098 _Antti Karttunen_, Feb 01 2016