OFFSET
0,4
COMMENTS
Inspired by the Japanese puzzle of the same name.
LINKS
Wikipedia, Heyawake.
FORMULA
a(n) = A239072(n-4) + 2*n - 2 for n > 4.
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
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 the suggestion of Greg Malen, Sep 02 2020
STATUS
approved