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 A308567 #6 Jun 11 2019 17:48:45
%S A308567 -1,-2,-1,-2,-3,-2,-1,-2,-3,-2,-3,-2,-1,-2,-3,-2,-3,-2,-3,-4,-3,-4,-5,
%T A308567 -4,-3,-2,-3,-4,-3,-2,-3,-4,-3,-4,-3,-4,-3,-4,-5,-4,-5,-4,-5,-4,-3,-4,
%U A308567 -5,-6,-7,-6,-5,-6,-5,-6,-5,-6,-5,-6,-5,-4,-5,-4,-5,-6,-5
%N A308567 Consider the second least-significant bits of the first n prime numbers: a(n) equals the number of zeros minus the number of ones.
%F A308567 a(n) = Sum_{k = 1..n} (-1)^A100672(n).
%F A308567 a(n) = 0 iff n belongs to A051024.
%F A308567 a(n) = -1-A038698(n).
%Y A308567 Cf. A038698, A051024, A100672.
%K A308567 sign,base
%O A308567 1,2
%A A308567 _Rémy Sigrist_, Jun 08 2019