%I M4121 #17 Aug 26 2019 03:18:30
%S 1,6,18,54,150,426,1158,3204,8682,23724,64194,174378,470856,1274430,
%T 3434826,9272346,24953004,67230288,180705126,486152604,1305430884,
%U 3507947838,9412114986,25268587338,67752451146,181754458194,487060621596,1305761069730,3497441209182
%N Number of n-step spirals on cubic lattice.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A. J. Guttmann and K. J. Wallace, <a href="https://doi.org/10.1088/0305-4470/18/16/010">On three-dimensional spiral anisotropic self-avoiding walks</a>, J. Phys. A 18 (1985), L1049-L1054.
%H Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a006/A006779.java">Java program</a> (github)
%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,walk
%O 0,2
%A _N. J. A. Sloane_
%E More terms from _Sean A. Irvine_, Aug 25 2019