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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.
4
8, 140, 1290, 7374, 32477, 116420, 358112, 976063, 2425756, 5560046, 11946923, 24274195, 46975815, 87140153
OFFSET
4,1
COMMENTS
Column 5 of triangle A234350.
Without the restriction "non-equivalent (mod D_3)" the numbers are given by A194133.
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
Sequence in context: A061996 A345650 A092703 * A212442 A185248 A228867
KEYWORD
nonn,more
AUTHOR
Heinrich Ludwig, Dec 30 2013
EXTENSIONS
a(14)-a(17) from Heinrich Ludwig, Apr 19 2016
STATUS
approved