A129875 - OEIS

%I #5 Mar 30 2013 04:53:35

%S 0,2,4,9,22,45,120,239

%N Sequence t_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 1,2

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