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%I M2738 #16 Aug 26 2019 04:27:11
%S 1,3,8,20,47,106,230,479,973,1924,3712,7021,13034,23780,42732,75703,
%T 132360,228664,390611,660296,1105321,1833358,3014694,4917036,7958127,
%U 12786252,20401469,32337878,50936233,79750436,124149022,192204697,296001288,453548269,691574373,1049590078
%N Number of n-step spirals on hexagonal lattice.
%C The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H Sean A. Irvine, <a href="/A006776/b006776.txt">Table of n, a(n) for n = 1..44</a>
%H Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a006/A006776.java">Java program</a> (github)
%H G. Nebe and N. J. A. Sloane, <a href="http://www.math.rwth-aachen.de/~Gabriele.Nebe/LATTICES/A2.html">Home page for hexagonal (or triangular) lattice A2</a>
%H G. Szekeres and A. J. Guttmann, <a href="https://doi.org/10.1088/0305-4470/20/2/033">Spiral self-avoiding walks on the triangular lattice</a>, J. Phys. A 20 (1987), 481-493.
%K nonn
%O 1,2
%A _N. J. A. Sloane_.
%E More terms from _Sean A. Irvine_, Aug 24 2019
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