

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, 84, 96, 108, 121, 132, 146, 161, 176, 190, 208
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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(n4)+2n2.


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 n4 X n4 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


STATUS

approved



