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Number of nonempty subsets of {1,2,...,n} in which exactly 1/4 of the elements are <= (n-4)/2.
0

%I #4 Mar 30 2012 18:56:54

%S 0,0,0,0,0,10,20,41,77,126,252,392,844,1270,2800,4070,9020,12782,

%T 28679,40022,91286,126048,291018,398125,926177,1256717,2942192,

%U 3965620,9343948,12526280,29689088,39617627,94363367

%N Number of nonempty subsets of {1,2,...,n} in which exactly 1/4 of the elements are <= (n-4)/2.

%K nonn

%O 1,6

%A _Clark Kimberling_