A337502 Minimum number of painted cells in an n X n grid to avoid unpainted tetrominoes.

0, 1, 3, 6, 9, 15, 20, 27, 34, 43

Offset

1,3

Links

Table of n, a(n) for n=1..10.

Example

For n = 4, painting only 5 cells would leave an unpainted tetromino, but painting the following 6 cells avoids all unpainted tetrominoes:
. . X .
X X . X
. . X .
. X . .

Crossrefs

Cf. A337501.

Sequence in context: A143981 A031940 A007187 * A082004 A364017 A352733

Adjacent sequences: A337499 A337500 A337501 * A337503 A337504 A337505

Keyword

nonn,more

Author

Rob Pratt, Aug 29 2020

Status

approved