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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 * A341569 A005463 A160896 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 July 20 20:16 EDT 2024. Contains 374459 sequences. (Running on oeis4.)