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A243214 Number of ways to place 5 points on a triangular grid of side n, so that no three of them are vertices of an equilateral triangle with sides parallel to the grid. 4
0, 63, 1566, 13971, 77124, 319206, 1083723, 3181401, 8344854, 20006349, 44548227, 93248628, 185176866, 351410664, 640972980, 1129067352, 1928196432, 3203016813 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

LINKS

Table of n, a(n) for n=3..20.

FORMULA

a(n) = (n^10 + 5*n^9 - 10*n^8)/3840 + O(n^7)

CROSSREFS

Cf. A243211, A243210, A000217, A050534, A243212, A243213.

Sequence in context: A132465 A202983 A107319 * A005463 A160896 A017779

Adjacent sequences:  A243211 A243212 A243213 * A243215 A243216 A243217

KEYWORD

nonn,more

AUTHOR

Heinrich Ludwig, Jun 10 2014

STATUS

approved

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Last modified August 4 19:15 EDT 2020. Contains 336202 sequences. (Running on oeis4.)