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A187175 Number of 5-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, 16, 136, 456, 1024, 1804, 2784, 3964, 5344, 6924, 8704, 10684, 12864, 15244, 17824, 20604, 23584, 26764, 30144, 33724, 37504, 41484, 45664, 50044, 54624, 59404, 64384, 69564, 74944, 80524, 86304, 92284, 98464, 104844, 111424, 118204, 125184 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

Row 5 of A187172.

LINKS

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

FORMULA

Empirical: a(n) = 100*n^2 - 920*n + 1984 for n>7.

G.f.: 4*x^5*(2 - x)*(2 + 12*x + 18*x^2 + 15*x^3 + 3*x^4) / (1 - x)^3 (conjectured). - Colin Barker, Apr 22 2018

EXAMPLE

Some solutions for 5 X 5:

..1..0..0..0..0....0..0..3..0..0....0..0..0..0..1....0..0..0..0..5

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

..0..2..0..0..0....0..0..0..4..0....3..0..0..0..0....1..0..0..0..0

..0..0..0..0..4....0..1..0..0..0....0..0..0..5..0....0..0..0..3..0

..0..0..5..0..0....0..0..0..0..5....0..4..0..0..0....0..2..0..0..0

CROSSREFS

Cf. A187172.

Sequence in context: A253303 A139616 A304506 * A302319 A303013 A059421

Adjacent sequences:  A187172 A187173 A187174 * A187176 A187177 A187178

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 06 2011

STATUS

approved

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Last modified January 22 04:27 EST 2020. Contains 331133 sequences. (Running on oeis4.)