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Sequence i_n arising in enumeration of arrays of directed blocks (see Quaintance reference for precise definition).
4

%I #5 Mar 30 2013 04:53:18

%S 2,4,14,52,210,888,3886,17448

%N Sequence i_n arising in enumeration of arrays of directed blocks (see Quaintance reference for precise definition).

%D Jocelyn Quaintance, Combinatoric Enumeration of Two-Dimensional Proper Arrays, Discrete Math., 307 (2007), 1844-1864.

%F See Quaintance reference for generating functions that produce A129872-A129886.

%K nonn,more

%O 1,1

%A _N. J. A. Sloane_, May 26 2007