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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
2, 24, 153, 713, 2557, 7661, 20055, 47153, 101821, 205322, 390580, 707708, 1229969, 2060777, 3344487 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

COMMENTS

Column 4 of triangle A234350.

Without the restriction "non-equivalent (mod D_3)" the numbers are given by A194132.

LINKS

Table of n, a(n) for n=3..17.

EXAMPLE

There are a(3) = 2 non-equivalent ways to arrange 4 indistinguishable points (x) on a triangular grid of side 3:

    x         .

   x x       x x

  . x .     x . x

CROSSREFS

Cf. A234350, A194132

Arranging 3 points: A234351

Arranging 5 points: A234353

Arranging 6 points: A234354

Sequence in context: A163752 A035600 A189247 * A241623 A288443 A108476

Adjacent sequences:  A234349 A234350 A234351 * A234353 A234354 A234355

KEYWORD

nonn,more

AUTHOR

Heinrich Ludwig, Dec 30 2013

EXTENSIONS

a(14)-a(17) from Heinrich Ludwig, Apr 19 2016

STATUS

approved

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Last modified May 25 01:58 EDT 2019. Contains 323534 sequences. (Running on oeis4.)