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%I #10 Apr 04 2016 16:14:05
%S 0,8,288,2208,9200,27720,68208,146048,282528,505800,851840,1365408,
%T 2101008,3123848,4510800,6351360,8748608,11820168,15699168,20535200,
%U 26495280,33764808,42548528,53071488,65580000,80342600,97651008
%N Number of 4-turn rook's tours on an n X n board summed over all starting positions
%C Row 4 of A187189
%H R. H. Hardin, <a href="/A187191/b187191.txt">Table of n, a(n) for n = 1..28</a>
%F Empirical: a(n) = 8*n^5 - 34*n^4 + 48*n^3 - 22*n^2.
%F Empirical G.f.: 8*x^2*(1+30*x+75*x^2+14*x^3)/(1-x)^6. [Colin Barker, Jan 22 2012]
%e Some solutions for 3X3
%e ..0..4..0....2..1..0....0..1..2....1..0..0....0..0..4....4..2..3....3..2..0
%e ..2..3..1....3..0..0....4..0..3....2..3..4....0..1..2....0..0..0....0..0..0
%e ..0..0..0....4..0..0....0..0..0....0..0..0....0..0..3....0..1..0....4..1..0
%K nonn
%O 1,2
%A _R. H. Hardin_ Mar 06 2011
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