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

Offset

1,2

Comments

See Gardner for precise definition.

References

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

Links

Table of n, a(n) for n=1..12.

Example

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

Crossrefs

Sequence in context: A210977 A049792 A062851 * A071979 A335323 A097748

Adjacent sequences: A178461 A178462 A178463 * A178465 A178466 A178467

Keyword

nonn

Author

N. J. A. Sloane, Dec 23 2010

Status

approved