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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 Table of n, a(n) for n=0..25. 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 Adjacent sequences: A239228 A239229 A239230 * A239232 A239233 A239234 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.)