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 A047193 #9 Jun 04 2013 12:11:43
%S A047193 0,0,2,3,4,14,20,27,83,119,164,494,714,1000,3002,4367,6187,18563,
%T A047193 27131,38759,116279,170543,245156,735470,1081574,1562274,4686824,
%U A047193 6906899,10015004,30045014,44352164,64512239,193536719,286097759
%N A047193 Number of nonempty subsets of {1,2,...,n} in which exactly 1/2 of the elements are <= n/3.
%F A047193 a(n) = C(n, [n/3]) - 1 = A051033(n) - 1. - _Ralf Stephan_, Mar 16 2004
%K A047193 nonn
%O A047193 1,3
%A A047193 _Clark Kimberling_