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A187176 Number of 6-step left-handed knight's tours (moves only out two, left one) on an n X n board summed over all starting positions. 1
0, 0, 0, 0, 0, 88, 496, 1440, 3064, 5344, 8208, 11640, 15640, 20208, 25344, 31048, 37320, 44160, 51568, 59544, 68088, 77200, 86880, 97128, 107944, 119328, 131280, 143800, 156888, 170544, 184768, 199560, 214920, 230848, 247344, 264408, 282040 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

COMMENTS

Row 6 of A187172.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..50

FORMULA

Empirical: a(n) = 284*n^2 - 3100*n + 7944 for n>9.

G.f.: 8*x^6*(11 + 29*x + 27*x^2 + 18*x^3 - 3*x^4 - 9*x^5 - 2*x^6) / (1 - x)^3 (conjectured). - Colin Barker, Apr 22 2018

EXAMPLE

Some solutions for 6 X 6:

..0..0..0..5..0..0....0..0..0..0..0..0....0..0..4..0..0..0....0..0..0..6..0..0

..0..6..0..0..0..0....0..0..0..0..6..0....3..0..0..0..0..0....0..1..0..0..0..0

..0..0..0..0..4..0....0..0..5..0..0..0....0..0..0..5..0..0....0..0..0..0..5..0

..0..0..1..0..0..0....4..0..0..0..0..1....0..2..0..0..0..0....0..0..2..0..0..0

..0..0..0..0..0..3....0..0..0..2..0..0....0..0..0..0..6..0....0..0..0..0..0..4

..0..0..0..2..0..0....0..3..0..0..0..0....0..0..1..0..0..0....0..0..0..3..0..0

CROSSREFS

Cf. A187172.

Sequence in context: A234770 A052049 A046378 * A236009 A236003 A183839

Adjacent sequences:  A187173 A187174 A187175 * A187177 A187178 A187179

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 06 2011

STATUS

approved

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Last modified January 19 17:59 EST 2020. Contains 331051 sequences. (Running on oeis4.)