cp's OEIS Frontend

A187193 Number of 6-turn rook's tours on an n X n board summed over all starting positions.

%I A187193 #15 Apr 19 2022 05:17:07
%S A187193 0,0,1440,40896,364800,1902240,7197120,21960960,57407616,133531200,
%T A187193 283488480,559247040,1038660480
%N A187193 Number of 6-turn rook's tours on an n X n board summed over all starting positions.
%F A187193 Empirical: a(n) = 32*n^7 - 258*n^6 + 846*n^5 - 1426*n^4 + 1234*n^3 - 428*n^2.
%F A187193 Empirical G.f.: 96*x^3*(15+306*x+812*x^2+503*x^3+44*x^4)/(1-x)^8. [_Colin Barker_, Jan 22 2012]
%e A187193 Some solutions for 3X3
%e A187193 ..0..0..1....0..0..6....3..2..1....0..0..1....0..4..5....0..0..3....0..3..2
%e A187193 ..3..4..2....0..4..5....0..0..0....4..6..5....1..0..0....0..5..4....6..0..0
%e A187193 ..0..5..6....2..3..1....4..5..6....3..0..2....2..3..6....1..6..2....5..4..1
%Y A187193 Row 6 of A187189.
%K A187193 nonn,more
%O A187193 1,3
%A A187193 _R. H. Hardin_, Mar 06 2011