%I A006861 M0786
%S A006861 1,2,3,6,11,21,40,77,149,289,563,1099,2152,4222,8299,16339,32217,63612,
               125753,
%T A006861 248870,493015,977576,1940042,3853117,7658211,15231219,30312012,60360046,
               120260317
%N A006861 Number of directed site animals on hexagonal lattice.
%C A006861 The hexagonal lattice is the familiar 2-dimensional lattice in which 
               each point has 6 neighbors. This is sometimes called the triangular 
               lattice.
%D A006861 D. Dhar et al., Enumeration of directed site animals on two-dimensional 
               lattices, J. Phys. A 15 (1982), L279-L284.
%D A006861 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%H A006861 G. Nebe and N. J. A. Sloane, <a href="http://www.research.att.com/~njas/
               lattices/A2.html">Home page for hexagonal (or triangular) lattice 
               A2</a>
%Y A006861 Sequence in context: A132832 A079116 A109222 this_sequence A052956 A008930 
               A164362
%Y A006861 Adjacent sequences: A006858 A006859 A006860 this_sequence A006862 A006863 
               A006864
%K A006861 nonn
%O A006861 1,2
%A A006861 Simon Plouffe, N. J. A. Sloane (njas(AT)research.att.com).