%I A129876
%S A129876 2,4,14,52,210,888,3886,17448
%N A129876 Sequence i_n arising in enumeration of arrays of directed blocks (see 
               Quaintance reference for precise definition).
%D A129876 Jocelyn Quaintance, Combinatoric Enumeration of Two-Dimensional Proper 
               Arrays, Discrete Math., 307 (2007), 1844-1864.
%F A129876 See Quaintance reference for generating functions that produce A129872-A129886.
%Y A129876 Sequence in context: A046650 A055727 A003500 this_sequence A038055 A006385 
               A131180
%Y A129876 Adjacent sequences: A129873 A129874 A129875 this_sequence A129877 A129878 
               A129879
%K A129876 nonn
%O A129876 1,1
%A A129876 N. J. A. Sloane (njas(AT)research.att.com), May 26 2007