%I A006776 M2738
%S A006776 1,3,8,20,47,106,230,479,973,1924,3712,7021,13034,23780,42732,75703,132360,
%T A006776 228664,390611,660296,1105321,1833358,3014694,4917036,7958127,12786252
%N A006776 Number of n-step spirals on hexagonal lattice.
%C A006776 The hexagonal lattice is the familiar 2-dimensional lattice in which 
               each point has 6 neighbors. This is sometimes called the triangular 
               lattice.
%D A006776 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006776 G. Szekeres and A. J. Guttmann, Spiral self-avoiding walks on the triangular 
               lattice, J. Phys. A 20 (1987), 481-493.
%H A006776 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 A006776 Sequence in context: A101533 A138803 A048492 this_sequence A050231 A136305 
               A026712
%Y A006776 Adjacent sequences: A006773 A006774 A006775 this_sequence A006777 A006778 
               A006779
%K A006776 nonn
%O A006776 1,2
%A A006776 N. J. A. Sloane (njas(AT)research.att.com).