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Number of nonempty subsets of {1,2,...,n} in which exactly 2/3 of the elements are <= (n-1)/3.
0

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

%S 0,0,0,0,0,0,5,6,7,21,24,27,90,105,121,385,450,520,1651,1939,2255,

%T 7175,8456,9877,31416,37122,43510,138510,164025,192801,614019,728409,

%U 858199,2734171,3248322,3834655,12220780,14536951,17189667

%N Number of nonempty subsets of {1,2,...,n} in which exactly 2/3 of the elements are <= (n-1)/3.

%K nonn

%O 1,7

%A _Clark Kimberling_