%I #13 Oct 12 2017 08:46:48
%S 7,88,1074,13002,157058,1896074,22886754,276246170,3334295986,
%T 40244915946,485755429442,5863058792506,70767006224978,
%U 854156391897098,10309651065637602,124437288171423322
%N Half the number of 4 X n binary arrays with no path of adjacent 1's or adjacent 0's from top row to bottom row.
%F Empirical (for n>=6): a(n) = 19*a(n-1) - 98*a(n-2) + 180*a(n-3) - 80*a(n-4) - 16*a(n-5). - _Vaclav Kotesovec_, Nov 28 2012
%F Empirical g.f.: x*(7 - 45*x + 88*x^2 - 40*x^3 - 8*x^4) / (1 - 19*x + 98*x^2 - 180*x^3 + 80*x^4 + 16*x^5). - _Colin Barker_, Oct 12 2017
%Y Cf. 2 X n A000079, n X 1 A000225, vertical path of 1 A069361-A069395, vertical paths of 0+1 A069396-A069416, vertical path of 1 not 0 A069417-A069428, no vertical paths A069429-A069447, no horizontal or vertical paths A069448-A069452.
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 22 2002