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%I #10 Jul 04 2018 05:13:18
%S 0,0,0,0,1,2,10,15,45,60,140,175,360,435,891,1071,2415,2940,7260,8910,
%T 22359,27345,66625,80795,191191,230230,541190,649805,1548755,1860131,
%U 4514979,5426995,13295955,15974220,39112716,46915104,114411173
%N Number of nonempty subsets of {1,2,...,n} in which exactly 1/5 of the elements are <= (n-2)/2.
%o (PARI) { a(n) = sum(i=1,n\5, binomial(n\2-1,i) * binomial(n+1-n\2,4*i) ) } \\ _Max Alekseyev_, Feb 09 2010
%K nonn
%O 1,6
%A _Clark Kimberling_
%E More terms from _Max Alekseyev_, Feb 09 2010
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