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 A124754 #5 Jul 24 2013 18:25:30
%S A124754 0,1,2,0,3,1,-1,1,4,2,0,2,-2,0,2,0,5,3,1,3,-1,1,3,1,-3,-1,1,-1,3,1,-1,
%T A124754 1,6,4,2,4,0,2,4,2,-2,0,2,0,4,2,0,2,-4,-2,0,-2,2,0,-2,0,4,2,0,2,-2,0,
%U A124754 2,0,7,5,3,5,1,3,5,3,-1,1,3,1,5,3,1,3,-3,-1,1,-1,3,1,-1,1,5,3,1,3,-1,1,3,1,-5,-3,-1,-3,1,-1,-3,-1,3
%N A124754 Alternating sum of compositions in standard order.
%C A124754 The standard order of compositions is given by A066099.
%C A124754 The sum of row n is 2^{n-1} for n>0.
%H A124754 Alois P. Heinz, <a href="/A124754/b124754.txt">Rows n = 0..14, flattened</a>
%F A124754 For a composition b(1),...,b(k), a(n) = Sum_{i=1}^k (-1)^{i-1} b(i).
%F A124754 a(2^k) = k+1. If n = 2^e_1 + 2^e_2 + k, 0 <= k < 2^e_2 < 2^e_1, then a(n) = (e_1 - e_2) - a(2^e_2 + k).
%F A124754 a(0) = 0; for n>0, a(n) = a(floor(n/2)) - A106400(n).
%e A124754 Composition number 11 is 2,1,1; 2-1+1 = 2, so a(11) = 2.
%e A124754 The table starts:
%e A124754 0
%e A124754 1
%e A124754 2 0
%e A124754 3 1 -1 1
%Y A124754 Cf. A066099, A070939, A124756, A011782 (row lengths), A106400.
%K A124754 easy,sign,tabf
%O A124754 0,3
%A A124754 _Franklin T. Adams-Watters_, Nov 06 2006