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 A308343 #11 May 22 2019 03:36:07
%S A308343 1,0,1,2,1,0,1,0,1,0,-1,-2,-1,0,1,0,1,2,3,4,3,2,1,0,1,0,-1,0,1,0,1,0,
%T A308343 1,2,1,2,3,2,1,0,1,0,1,2,3,2,1,2,3,4,5,6,5,6,5,4,5,4,3,2,1,0,1,2,1,0,
%U A308343 1,2,1,0,-1,-2,-3,-4,-3,-4,-3,-4,-3,-4,-5,-4
%N A308343 a(n) is the difference between the number of zeros and the number of ones among the first n terms of the Ehrenfeucht-Mycielski sequence A038219.
%H A308343 Rémy Sigrist, <a href="/A308343/b308343.txt">Table of n, a(n) for n = 1..10000</a>
%H A308343 Rémy Sigrist, <a href="/A308343/a308343.png">Scatterplot of the first 500000 terms</a>
%H A308343 Rémy Sigrist, <a href="/A308343/a308343.pl.txt">Perl program for A308343</a>
%F A308343 a(n) = Sum_{k = 1..n} (-1)^A038219(k).
%e A308343 The first terms, alongside the numbers of zeros and of ones and A038219(n), are:
%e A308343 n a(n) #0's #1's A038219(n)
%e A308343 -- ---- ---- ---- ----------
%e A308343 1 1 1 0 0
%e A308343 2 0 1 1 1
%e A308343 3 1 2 1 0
%e A308343 4 2 3 1 0
%e A308343 5 1 3 2 1
%e A308343 6 0 3 3 1
%e A308343 7 1 4 3 0
%e A308343 8 0 4 4 1
%e A308343 9 1 5 4 0
%e A308343 10 0 5 5 1
%e A308343 11 -1 5 6 1
%e A308343 12 -2 5 7 1
%o A308343 (Perl) See Links section.
%Y A308343 Cf. A038219.
%K A308343 sign
%O A308343 1,4
%A A308343 _Rémy Sigrist_, May 21 2019