Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #7 Apr 04 2016 16:14:06
%S 0,0,35328,1533064,10353632,33908456,76860784,140714528,225295032,
%T 330074144,454720992,599118736,763244128,947095136,1150671760,
%U 1373974000,1617001856,1879755328,2162234416,2464439120,2786369440,3128025376
%N Number of 7-step king-knight's tours (piece capable of both kinds of moves) on an n X n board summed over all starting positions
%C Row 7 of A187850
%H R. H. Hardin, <a href="/A187855/b187855.txt">Table of n, a(n) for n = 1..50</a>
%F Empirical: a(n) = 9862808*n^2 - 82444808*n + 168212080 for n>11
%e Some solutions for 4X4
%e ..2..0..0..0....0..5..2..0....0..0..6..0....0..0..1..3....0..0..1..2
%e ..1..3..4..0....1..6..7..0....0..2..1..0....0..4..2..6....0..0..0..3
%e ..0..5..6..0....0..3..4..0....4..5..0..7....0..7..0..5....0..6..4..0
%e ..0..0..7..0....0..0..0..0....3..0..0..0....0..0..0..0....0..0..5..7
%K nonn
%O 1,3
%A _R. H. Hardin_ Mar 14 2011