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A239231
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Heyawake numbers: maximum number of painted cells in an n X n grid, such that no two painted cells are orthogonally adjacent and the unpainted cells form a contiguous area.
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2
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0, 1, 1, 4, 5, 9, 12, 17, 21, 27, 33, 41, 48, 56, 65, 75, 85, 96, 108, 121, 133, 146, 161, 176, 190, 208
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OFFSET
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0,4
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COMMENTS
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Inspired by the Japanese puzzle of the same name.
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LINKS
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FORMULA
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a(n) = A239072(n-4) + 2*n - 2 for n > 4.
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EXAMPLE
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If n=6, the painted cells could be A1, A3, A6, B5, C1, C3, D4, D6, E2, F1, F4, F6 (12 cells in all).
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CROSSREFS
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Cf. A239072 (makes up the inner n-4 X n-4 square of the grid).
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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Some values corrected, incorrect values removed by Elliott Line, Aug 21 2014
a(16) and a(20) corrected by Elliott Line at the suggestion of Greg Malen, Sep 02 2020
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STATUS
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approved
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