%I #13 Apr 19 2016 07:47:22
%S 2,24,153,713,2557,7661,20055,47153,101821,205322,390580,707708,
%T 1229969,2060777,3344487
%N Number of non-equivalent (mod D_3) ways to arrange 4 indistinguishable points on a triangular grid of side n so that no three points are collinear.
%C Column 4 of triangle A234350.
%C Without the restriction "non-equivalent (mod D_3)" the numbers are given by A194132.
%e There are a(3) = 2 non-equivalent ways to arrange 4 indistinguishable points (x) on a triangular grid of side 3:
%e x .
%e x x x x
%e . x . x . x
%Y Cf. A234350, A194132
%Y Arranging 3 points: A234351
%Y Arranging 5 points: A234353
%Y Arranging 6 points: A234354
%K nonn,more
%O 3,1
%A _Heinrich Ludwig_, Dec 30 2013
%E a(14)-a(17) from _Heinrich Ludwig_, Apr 19 2016
|