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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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Row 4 of A188777 LINKS R. H. Hardin, Table of n, a(n) for n = 1..42 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 * A262291 A267838 A045543 Adjacent sequences:  A188776 A188777 A188778 * A188780 A188781 A188782 KEYWORD nonn AUTHOR R. H. Hardin Apr 10 2011 STATUS approved

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Last modified January 19 17:26 EST 2022. Contains 350466 sequences. (Running on oeis4.)