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

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

%S 0,0,0,0,2,8,20,41,63,126,252,505,1000,1936,3652,7305,14313,27573,

%T 52325,97868,180404,327692,586568,1034930,2718254,5012504,9131804,

%U 16440929,29259404,51482510,89575460,154146135,262403715,441956955

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

%K nonn

%O 1,5

%A _Clark Kimberling_