This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 19 03:05 EDT 2018. Contains 315155 sequences. (Running on oeis4.)