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A188779
Number of 4-turn bishop's tours on an n X n board summed over all starting positions
1
0, 0, 24, 328, 1720, 5816, 15424, 34736, 69776, 128528, 221448, 361528, 564872, 850696, 1241968, 1765344, 2451872, 3336864, 4460664, 5868456, 7611096, 9744856, 12332320, 15442064, 19149616, 23537072, 28694120, 34717592, 41712552, 49791784
OFFSET
1,3
COMMENTS
Row 4 of A188777
LINKS
FORMULA
Empirical: a(n) = 4*a(n-1) -4*a(n-2) -4*a(n-3) +10*a(n-4) -4*a(n-5) -4*a(n-6) +4*a(n-7) -a(n-8)
Contribution from Vaclav Kotesovec, Sep 01 2012: (Start)
Empirical: G.f.: 8*x^3*(3 + 29*x + 63*x^2 + 43*x^3 + 14*x^4)/((1-x)^6*(1+x)^2)
Empirical: a(n) = -2 + 257*n/15 - 109*n^2/3 + 106*n^3/3 - 47*n^4/3 + 38*n^5/15 + (-1)^n*(2-n)
(End)
EXAMPLE
Some solutions for 4X4
..0..0..0..1....0..0..0..0....0..0..1..0....0..0..0..0....0..4..0..1
..0..0..3..0....1..0..0..0....0..4..0..2....0..4..0..2....3..0..0..0
..0..4..0..0....0..2..0..4....0..0..3..0....0..0..3..0....0..2..0..0
..2..0..0..0....0..0..3..0....0..0..0..0....0..1..0..0....0..0..0..0
CROSSREFS
Sequence in context: A004317 A295250 A295649 * A267838 A045543 A125459
KEYWORD
nonn
AUTHOR
R. H. Hardin Apr 10 2011
STATUS
approved