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A234352 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. 4

%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

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Last modified March 28 10:55 EDT 2024. Contains 371241 sequences. (Running on oeis4.)