OFFSET
0,2
COMMENTS
The holes must not touch each other.
REFERENCES
Jean-Paul Delahaye, Des trous à entourer avec parcimonie, Pour las science, No. 501, Juillet 2019, pp. 82-87.
EXAMPLE
Examples from N. J. A. Sloane, Jan 30 2019 for n=1, 2, 3:
XXX
XOX
XXX
---
XXXXX
XOXOX
XXXXX
-----
XXXXXXX
XOXOXOX
XXXXXXX
CROSSREFS
KEYWORD
nonn
AUTHOR
Jean-Paul Delahaye, Sep 30 2018
EXTENSIONS
Entry 123 changed to 124 by the author, Jul 01 2019. - N. J. A. Sloane, Jul 01 2019
STATUS
approved