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A239231 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. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
COMMENTS
Inspired by the Japanese puzzle of the same name.
LINKS
Wikipedia, Heyawake
FORMULA
If n>4, a(n) = A239072(n-4)+2*n-2.
EXAMPLE
For example, if n=6, the painted cells could be A1, A3, A6, B5, C1, C3, D4, D6, E2, F1, F4, F6 (12 cells in all).
CROSSREFS
Cf. A239072 (makes up the inner n-4 X n-4 square of the grid).
Sequence in context: A200535 A010405 A125603 * A078507 A060199 A229240
KEYWORD
nonn,more
AUTHOR
Elliott Line, Mar 13 2014
EXTENSIONS
Some values corrected, incorrect values removed by Elliott Line, Aug 21 2014
a(16) and a(20) corrected by Elliott Line at suggestion of Greg Malen, Sep 02 2020
STATUS
approved

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Last modified February 23 07:33 EST 2024. Contains 370269 sequences. (Running on oeis4.)