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 A188778 Number of 3-turn bishop's tours on an n X n board summed over all starting positions 1
 0, 0, 28, 152, 488, 1192, 2468, 4560, 7760, 12400, 18860, 27560, 38968, 53592, 71988, 94752, 122528, 156000, 195900, 243000, 298120, 362120, 435908, 520432, 616688, 725712, 848588, 986440, 1140440, 1311800, 1501780, 1711680, 1942848, 2196672 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Row 3 of A188777 LINKS R. H. Hardin, Table of n, a(n) for n = 1..42 FORMULA Empirical: a(n) = 4*a(n-1) -5*a(n-2) +5*a(n-4) -4*a(n-5) +a(n-6) Contribution from Vaclav Kotesovec, Sep 01 2012: (Start) Empirical: G.f.: 4*x^3*(7 + 10*x + 5*x^2)/((1-x)^5*(1+x)) Empirical: a(n) = 1/4 - 10*n/3 + 23*n^2/3 - 20*n^3/3 + 11*n^4/6 - (-1)^n/4 (End) EXAMPLE Some solutions for 4X4 ..0..0..0..0....0..0..0..1....1..0..0..0....0..0..0..0....0..0..2..0 ..1..0..0..0....0..0..0..0....0..3..0..0....3..0..0..0....0..0..0..3 ..0..3..0..0....0..2..0..0....0..0..0..0....0..1..0..0....1..0..0..0 ..0..0..2..0....0..0..3..0....0..0..0..2....0..0..2..0....0..0..0..0 CROSSREFS Sequence in context: A028380 A219887 A271636 * A002593 A015881 A026910 Adjacent sequences: A188775 A188776 A188777 * A188779 A188780 A188781 KEYWORD nonn AUTHOR R. H. Hardin Apr 10 2011 STATUS approved

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Last modified September 9 14:16 EDT 2024. Contains 375764 sequences. (Running on oeis4.)