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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A143891 Number of ways of placing kings with no more than 4 mutual attacks on an n X n chessboard symmetric about the diagonal and under 90-degree rotation. 2
1, 2, 1, 5, 2, 15, 7, 68, 23, 370, 104, 2649, 571, 25209, 4176, 313503, 39827, 5212881, 500254, 114569731, 8348616 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..20.

CROSSREFS

Sequence in context: A192263 A109738 A258307 * A030400 A115345 A194092

Adjacent sequences:  A143888 A143889 A143890 * A143892 A143893 A143894

KEYWORD

nonn,more,hard

AUTHOR

R. H. Hardin, Sep 04 2008

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 21 14:41 EDT 2019. Contains 328301 sequences. (Running on oeis4.)