A234353 - OEIS

A234353

Number of non-equivalent (mod D_3) ways to arrange 5 indistinguishable points on a triangular grid of side n so that no three points are collinear.

8, 140, 1290, 7374, 32477, 116420, 358112, 976063, 2425756, 5560046, 11946923, 24274195, 46975815, 87140153

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OFFSET

4,1

COMMENTS

Column 5 of triangle A234350.

Without the restriction "non-equivalent (mod D_3)" the numbers are given by A194133.

LINKS

EXAMPLE

There are a(4) = 8 non-equivalent ways to arrange 5 indistinguishable points (x) on a triangular grid of side 4. Some examples:

x x . . .

x x . . x . x x x .

. . . x . x x . x . x . x . x

. x x . . x x . . x x . x . . x . x . x

CROSSREFS

Arranging 3 points: A234351

Arranging 4 points: A234352

Arranging 6 points: A234354

KEYWORD

nonn,more

AUTHOR

EXTENSIONS

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

STATUS

approved