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 A241225 Number of right triangles on a centered hexagonal grid of size n. 4
 0, 12, 216, 1104, 3708, 9396, 20304, 38868, 68364, 112632, 176076, 263832, 381924, 536424, 735240, 985896, 1296540, 1676508, 2137392, 2689248, 3344244, 4114020 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A centered hexagonal grid of size n is a grid with A003215(n-1) points forming a hexagonal lattice. LINKS Eric Weisstein's World of Mathematics, Hex Number. Eric Weisstein's World of Mathematics, Right Triangle. FORMULA a(n) = A241223(n) - A241224(n) - A241226(n). CROSSREFS Cf. A077435. Sequence in context: A262739 A027487 A276245 * A274956 A116164 A268369 Adjacent sequences:  A241222 A241223 A241224 * A241226 A241227 A241228 KEYWORD nonn AUTHOR Martin Renner, Apr 17 2014 EXTENSIONS a(7) from Martin Renner, May 31 2014 a(8)-a(22) from Giovanni Resta, May 31 2014 STATUS approved

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Last modified June 26 18:18 EDT 2022. Contains 354885 sequences. (Running on oeis4.)