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A187287
Number of 2-step one or two space at a time rook's tours on an n X n board summed over all starting positions.
1
0, 8, 36, 80, 140, 216, 308, 416, 540, 680, 836, 1008, 1196, 1400, 1620, 1856, 2108, 2376, 2660, 2960, 3276, 3608, 3956, 4320, 4700, 5096, 5508, 5936, 6380, 6840, 7316, 7808, 8316, 8840, 9380, 9936, 10508, 11096, 11700, 12320, 12956, 13608, 14276, 14960, 15660
OFFSET
1,2
LINKS
FORMULA
Empirical: a(n) = 8*n^2 - 12*n for n>1.
Empirical g.f.: 4*x^2*(2+3*x-x^2)/(1-x)^3. - Colin Barker, Jan 22 2012
EXAMPLE
Some solutions for 4 X 4:
..0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....0..2..0..1
..1..0..0..0....0..1..0..0....0..1..2..0....2..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
..2..0..0..0....0..2..0..0....0..0..0..0....1..0..0..0....0..0..0..0
MAPLE
A187287:=n->`if`(n=1, 0, 8*n^2 - 12*n); seq(A187287(n), n=1..50); # Wesley Ivan Hurt, Feb 28 2014
CROSSREFS
Row 2 of A187286.
Cf. A014107.
Sequence in context: A139608 A321778 A009923 * A224159 A321251 A035006
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 08 2011
STATUS
approved