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 A271907 Size of the largest subset S of the points of an n X n square grid such that no three of the points of S form an isosceles triangle. 3
 1, 2, 4, 6, 8, 10, 12, 14, 16, 18 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS S must not contain 3 points A,B,C such that |AB| = |BC|. For example, this configuration is forbidden:    O O O B    O O O O    A O O O    O C O O It appears that this is simply a(n) = 2n-2 for n>1, and if so this entry may be replaced by a comment in A271914 and A271906, and this A-number recycled. LINKS EXAMPLE Illustration for a(3) = 4:    O X X    X O O    X O O Illustration for a(8) = 14:    O X X X X X O X    X O O O O O O X    X O O O O O O O    X O O O O O O O    X O O O O O O O    X O O O O O O O    O O O O O O O O    X X O O O O O O CROSSREFS Cf. A271906, A227133. Main diagonal of A271914. Sequence in context: A319747 A055958 A241142 * A069816 A088116 A100817 Adjacent sequences:  A271904 A271905 A271906 * A271908 A271909 A271910 KEYWORD nonn,more AUTHOR Giovanni Resta and N. J. A. Sloane, Apr 22 2016 STATUS approved

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Last modified July 29 17:41 EDT 2021. Contains 346346 sequences. (Running on oeis4.)