A178464 - OEIS

A178464

Minimal number of lines that must be removed from an n X n square array of cells in order to break all rectangles.

1, 3, 7, 11, 18, 25, 34, 43, 55, 67, 82, 97

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

See Gardner for precise definition.

REFERENCES

M. Gardner, Mathematical Carnival, Random House, NY, 1975; page 120.

LINKS

EXAMPLE

To illustrate a(2) = 3: remove edges A, B and C:

--A----

| | |

-----B-

| C |

-------

CROSSREFS

KEYWORD

nonn

AUTHOR

STATUS

approved