login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A238381 Minimal number of V-trominoes needed to prevent any further V-trominoe from being placed on an n X n grid. 1
0, 1, 2, 3, 4, 6, 8, 11, 14, 18, 21, 25, 30, 35, 40 (list; graph; refs; listen; history; text; internal format)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 22 19:53 EDT 2019. Contains 328319 sequences. (Running on oeis4.)