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 A047167 #8 Apr 11 2021 22:15:50
%S A047167 0,0,0,0,0,3,6,24,40,100,150,315,455,980,1470,3528,5544,13692,21630,
%T A047167 51600,80520,186945,290400,675675,1056627,2492919,3929926,9324406,
%U A047167 14742910,34860553,55107598,129804808,205272008,483483128,765991032,1807560972,2869786524,6779169543
%N A047167 Number of nonempty subsets of {1,2,...,n} in which exactly 3/5 of the elements are <= n/2.
%H A047167 Andrew Howroyd, <a href="/A047167/b047167.txt">Table of n, a(n) for n = 1..500</a>
%F A047167 a(n) = Sum_{k>=1} binomial(floor(n/2), 3*k)*binomial(ceiling(n/2), 2*k). - _Andrew Howroyd_, Apr 11 2021
%o A047167 (PARI) a(n) = {my(m=n\2); sum(k=1, m\3, binomial(m, 3*k)*binomial(n-m, 2*k))} \\ _Andrew Howroyd_, Apr 11 2021
%Y A047167 Cf. A047165.
%K A047167 nonn
%O A047167 1,6
%A A047167 _Clark Kimberling_
%E A047167 Terms a(35) and beyond from _Andrew Howroyd_, Apr 11 2021