A337501 - OEIS

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A337501

Minimum number of painted cells in an n X n grid to avoid unpainted trominoes.

%I #9 Aug 30 2020 03:04:38

%S 0,2,4,8,11,18,23,32,39,50

%N Minimum number of painted cells in an n X n grid to avoid unpainted trominoes.

%e For n = 3, painting only 3 cells would leave an unpainted tromino, but painting the following 4 cells avoids all unpainted trominoes:

%e . . X

%e X X .

%e . . X

%K nonn,more

%O 1,2

%A _Rob Pratt_, Aug 29 2020