cp's OEIS Frontend

A187855 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.

%I A187855 #9 Jul 22 2025 10:55:18
%S A187855 0,0,35328,1533064,10353632,33908456,76860784,140714528,225295032,
%T A187855 330074144,454720992,599118736,763244128,947095136,1150671760,
%U A187855 1373974000,1617001856,1879755328,2162234416,2464439120,2786369440,3128025376
%N A187855 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 A187855 Row 7 of A187850
%H A187855 R. H. Hardin, <a href="/A187855/b187855.txt">Table of n, a(n) for n = 1..50</a>
%F A187855 Empirical: a(n) = 9862808*n^2 - 82444808*n + 168212080 for n>11
%e A187855 Some solutions for 4X4
%e A187855 ..2..0..0..0....0..5..2..0....0..0..6..0....0..0..1..3....0..0..1..2
%e A187855 ..1..3..4..0....1..6..7..0....0..2..1..0....0..4..2..6....0..0..0..3
%e A187855 ..0..5..6..0....0..3..4..0....4..5..0..7....0..7..0..5....0..6..4..0
%e A187855 ..0..0..7..0....0..0..0..0....3..0..0..0....0..0..0..0....0..0..5..7
%K A187855 nonn
%O A187855 1,3
%A A187855 _R. H. Hardin_ Mar 14 2011