%I #9 Aug 16 2018 13:22:52
%S 1,2,3,7,20,67,255,1080,5016,25249,136289,780658,4696002,29374011,
%T 189373083,1248978556,8376922028,56874440053,389553674037,
%U 2685020105574,18589701176694,129115803986575,898809701733551,6266899328414512
%N Number of n X 1 0..7 arrays with no element equal to another at a city block distance of exactly two, and new values 0..7 introduced in row major order.
%C Column 1 of A222894.
%H R. H. Hardin, <a href="/A222890/b222890.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 22*a(n-1) - 190*a(n-2) + 820*a(n-3) - 1849*a(n-4) + 2038*a(n-5) - 840*a(n-6) for n>8.
%F Empirical g.f.: x*(1 + x)*(1 - 21*x + 170*x^2 - 669*x^3 + 1314*x^4 - 1157*x^5 + 309*x^6) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - 4*x)*(1 - 5*x)*(1 - 7*x)). - _Colin Barker_, Aug 16 2018
%e All solutions for n=3:
%e ..0....0....0
%e ..0....1....1
%e ..1....1....2
%Y Cf. A222894.
%K nonn
%O 1,2
%A _R. H. Hardin_, Mar 08 2013