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 A242821 #9 May 24 2014 18:00:49 %S A242821 1,0,0,2,3,11,14,33,43,82,141,260,514,1049,2321,4789,10454,21735, %T A242821 46213,94782,196060,398662,810178,1631089,3278372,6556096,13088339, %U A242821 26063238,51824061,102926784,204239173,405087125,803109813,1592179369,3156298826,6258390137 %N A242821 Number of compositions of n with equal number of even and odd parts, both counted without multiplicity. %H A242821 Alois P. Heinz, <a href="/A242821/b242821.txt">Table of n, a(n) for n = 0..500</a> %e A242821 a(3) = 2: [1,2], [2,1]. %e A242821 a(4) = 3: [1,1,2], [1,2,1], [2,1,1]. %e A242821 a(5) = 11: [1,1,1,2], [1,1,2,1], [1,2,1,1], [2,1,1,1], [1,2,2], [2,1,2], [2,2,1], [2,3], [3,2], [1,4], [4,1]. %e A242821 a(6) = 14: [1,1,1,1,2], [1,1,1,2,1], [1,1,2,1,1], [1,2,1,1,1], [2,1,1,1,1], [1,1,2,2], [1,2,1,2], [1,2,2,1], [2,1,1,2], [2,1,2,1], [2,2,1,1], [1,1,4], [1,4,1], [4,1,1]. %Y A242821 Column k=0 of A242626. %Y A242821 Cf. A098123 (counted with multiplicity). %K A242821 nonn %O A242821 0,4 %A A242821 _Alois P. Heinz_, May 23 2014