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A051754 Consider problem of placing N queens on an n X n board so that each queen attacks precisely 1 other. Sequence gives maximal number of queens. 12
2, 2, 4, 4, 8, 8, 10, 12, 12, 14 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

2*[2n/3] is an upper bound for a(n), which is achieved for n=2, 4 and 6-14. - Jud McCranie, Aug 12 2001

REFERENCES

Martin Gardner, The Last Recreations, Copernicus, NY, 1997, 274-283.

LINKS

Table of n, a(n) for n=2..11.

CROSSREFS

Cf. A051755-A051759, A051567-A051571, A019654.

Sequence in context: A190172 A059867 A046971 * A108747 A116931 A206558

Adjacent sequences:  A051751 A051752 A051753 * A051755 A051756 A051757

KEYWORD

nonn,nice

AUTHOR

Robert Trent (trentrd(AT)hotmail.com), Aug 23 2000

STATUS

approved

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Last modified December 21 20:27 EST 2014. Contains 252326 sequences.