A137334 - OEIS

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A137334

Number of n X n crossword puzzles with dihedral symmetry group, for n odd. Acceptable crossword puzzles must have all words of length 3 or more, at least one word in each row and each column and be connected.

1, 2, 10, 45, 302, 3102, 45795 (list; graph; refs; listen; history; internal format)

	OFFSET	`3,2`
	COMMENTS	`The number of such puzzles for an even n = 2m is equal to the number of (2m-1) X (2m-1) puzzles.`
	LINKS	`Marc Brodie, Mathematica program`
	EXAMPLE	`a(5) = 2 because, using 0s for white squares and 1s for black squares, the only two 5x5 puzzles with dihedral symmetry group are:` `00000` `00000` `00000` `00000` `00000` `and` `10001` `00000` `00000` `00000` `10001`
	CROSSREFS	`Cf. A130578, A133226, A133253, A133258.` `Sequence in context: A192704 A005963 A140588 * A191813 A181294 A080643` `Adjacent sequences: A137331 A137332 A137333 * A137335 A137336 A137337`
	KEYWORD	`nonn`
	AUTHOR	`Marc Brodie (mbrodie(AT)wju.edu), Apr 07 2008`

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Last modified February 17 07:27 EST 2012. Contains 205998 sequences.