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Search: id:A064280
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| A064280 |
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Number of distinct solutions to the order n checkerboard problem, symmetrical solutions excluded: place n pieces on an n X n board so there is exactly one piece in each row, column and main diagonal. |
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+0
2
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OFFSET
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1,5
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REFERENCES
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Geoffrey Chase, Creative Computing 6(1), Jan 1980, 122.
Bahairiv Joshi, Unique Solutions to the Checkerboard Problem, Creative Computing 6(10), Oct 1980, 124-125.
Abijah Reed, Creative Computing 6(5), May 1980, 94.
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EXAMPLE
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The 4 X 4 solution is unique, excluding symmetrical solutions, with pieces at (1,1), (2,3), (3,4) and (4,2).
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CROSSREFS
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A007016 gives the number of solutions including symmetrical ones.
Cf. A007016.
Sequence in context: A027145 A010370 A081214 this_sequence A096424 A009629 A009651
Adjacent sequences: A064277 A064278 A064279 this_sequence A064281 A064282 A064283
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KEYWORD
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more,nonn
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AUTHOR
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Jud McCranie (j.mccranie(AT)comcast.net), Sep 24 2001
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