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A261595 Triangular array T(n, k) read by rows (n >= 1, 1 <= k <= n): row n gives the lexicographically earliest doubly centro-symmetric characteristic solution to the n queens problem, or n zeros if no doubly centro-symmetric characteristic solution exists. The k-th queen is placed in square (k, T(n, k)). 2
1, 0, 0, 0, 0, 0, 2, 4, 1, 3, 2, 5, 3, 1, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,7

COMMENTS

See the comments under A260318.

REFERENCES

Maurice Kraitchik: Mathematical Recreations. Mineola, NY: Dover, 2nd ed. 1953, pp. 247-255 (The Problem of the Queens).

LINKS

Table of n, a(n) for n=1..66.

EXAMPLE

n = 1: 1 is the trivial solution.

2 <= n < 4: no doubly centro-symmetric solutions exist.

n = 4: 2413 is the first and only solution.

       .*..

       ...*

       *...

       ..*.

n = 5: 25314 is the first and only solution.

6 <= n < 12: no doubly centro-symmetric solutions exist.

Triangle starts:

1;

0, 0;

0, 0, 0;

2, 4, 1, 3;

2, 5, 3, 1, 4;

0, 0, 0, 0, 0, 0;

...

CROSSREFS

Cf. A141843, A260318, A261596, A261597.

Sequence in context: A190555 A141843 A130266 * A211197 A258246 A258240

Adjacent sequences:  A261592 A261593 A261594 * A261596 A261597 A261598

KEYWORD

nonn,tabl

AUTHOR

Martin Renner, Aug 25 2015

STATUS

approved

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Last modified January 24 04:31 EST 2018. Contains 298115 sequences.