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A187292
Number of 7-step one or two space at a time rook's tours on an n X n board summed over all starting positions.
1
0, 0, 2304, 47648, 228512, 616752, 1241936, 2102944, 3192912, 4505424, 6037932, 7789392, 9759616, 11948560, 14356224, 16982608, 19827712, 22891536, 26174080, 29675344, 33395328, 37334032, 41491456, 45867600, 50462464, 55276048, 60308352
OFFSET
1,3
COMMENTS
Row 7 of A187286.
LINKS
FORMULA
Empirical: a(n) = 109360*n^2 - 763776*n + 1206864 for n>11.
Conjectures from Colin Barker, Apr 23 2018: (Start)
G.f.: 4*x^3*(576 + 10184*x + 23120*x^2 + 17964*x^3 + 7392*x^4 - 280*x^5 - 1716*x^6 - 1604*x^7 - 637*x^8 - 261*x^9 - 47*x^10 - 11*x^11) / (1 - x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>14.
(End)
EXAMPLE
Some solutions for 4 X 4:
..0..0..0..0....0..0..0..0....0..1..0..0....2..3..0..0....6..5..7..0
..0..5..6..4....0..0..7..0....3..2..7..0....1..5..7..6....0..0..0..0
..1..2..0..3....4..1..5..0....5..0..6..0....0..4..0..0....0..4..0..3
..0..0..7..0....3..2..6..0....4..0..0..0....0..0..0..0....0..1..0..2
CROSSREFS
Cf. A187286.
Sequence in context: A204102 A177759 A218431 * A235423 A235419 A229698
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 08 2011
STATUS
approved