A047182 - OEIS

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A047182

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

%I #9 Jun 04 2013 12:11:17

%S 0,0,0,3,4,14,20,55,83,209,329,791,1286,3002,5004,11439,19447,43757,

%T 75581,167959,293929,646645,1144065,2496143,4457399,9657699,17383859,

%U 37442159,67863914,145422674,265182524,565722719,1037158319

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

%F a(n) = C(n, [(n-2)/2]) - 1 = A037955(n) - 1. - _Ralf Stephan_, Mar 16 2004

%K nonn

%O 1,4

%A _Clark Kimberling_