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 A295223 Number of tilings of the n X n torus, using diagonal lines to connect the gridpoints. 2
 1, 4, 18, 669 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Peter Kagey, The eighteen tilings of the 3 x 3 torus. EXAMPLE For n = 3, the following four tilings are considered equivalent: *---*->-+---+   +---+->-*---*   *---*->-+---+   +---+->-+---+ | / | \ | \ |   | / | / | \ |   | \ | / | / |   | / | \ | \ | *---*---+---+   +---+---*---*   *---*---+---+   *---*---+---+ ^ / | / | \ ^ = ^ / | \ | \ ^ = ^ \ | / | \ ^ = ^ \ | / | / ^ +---+---+---+   +---+---+---+   +---+---+---+   *---*---+---+ | \ | / | / |   | \ | \ | / |   | / | \ | \ |   | \ | / | \ | +---+->-+---+   +---+->-+---+   +---+->-+---+   +---+->-+---+ The transformations are horizontal reflection, shifting to the right, and shifting down. CROSSREFS Cf. A295229. Sequence in context: A086400 A082022 A114574 * A173222 A156491 A287677 Adjacent sequences:  A295220 A295221 A295222 * A295224 A295225 A295226 KEYWORD nonn,more AUTHOR Peter Kagey, Nov 17 2017 STATUS approved

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Last modified January 20 22:57 EST 2020. Contains 331104 sequences. (Running on oeis4.)