A238381 Minimal number of V-trominoes needed to prevent any further V-trominoe from being placed on an n X n grid.

0, 1, 2, 3, 4, 6, 8, 11, 14, 18, 21, 25, 30, 35, 40

Offset

1,3

Comments

The V-trominoes must line up with the squares on the grid (skew placements are not allowed).

a(n) is the independent domination number of a graph with one node per tromino and an edge for each pair of trominoes that conflict. - Rob Pratt, Oct 02 2019

Links

Table of n, a(n) for n=1..15.

Juris Cernenoks, Illustration of initial terms

Erich Friedman, Problem of the Month (June 2000)

Crossrefs

Cf. A226918.

Sequence in context: A056829 A211536 A071764 * A290743 A059291 A177339

Adjacent sequences: A238378 A238379 A238380 * A238382 A238383 A238384

Keyword

nonn,more

Author

Juris Cernenoks, Feb 25 2014

Extensions

a(13)-a(15) from Rob Pratt, Oct 02 2019

Status

approved