cp's OEIS Frontend

A221694 Number of 2 X n arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, without consecutive moves in the same direction.

%I A221694 #8 Aug 10 2018 17:33:35
%S A221694 1,21,152,1336,11036,92660,774380,6479664,54200980,453418640,
%T A221694 3792991120,31729761276,265430689860,2220422566716,18574626389432,
%U A221694 155383375746468,1299837358873328,10873603138412824,90961568659281764,760925966163564220
%N A221694 Number of 2 X n arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, without consecutive moves in the same direction.
%C A221694 Row 2 of A221693.
%H A221694 R. H. Hardin, <a href="/A221694/b221694.txt">Table of n, a(n) for n = 1..210</a>
%F A221694 Empirical: a(n) = 5*a(n-1) + 28*a(n-2) + 9*a(n-3) - 62*a(n-4) - 30*a(n-5) + 64*a(n-6) + 32*a(n-7) - 32*a(n-8) + 32*a(n-9).
%F A221694 Empirical g.f.: x*(1 + 16*x + 19*x^2 - 21*x^3 - 27*x^4 + 36*x^5 + 38*x^6 - 24*x^7 + 24*x^8) / ((1 + 2*x)^2*(1 - 9*x + 4*x^2 + 11*x^3 + 2*x^4 - 22*x^5 + 16*x^6 - 8*x^7)). - _Colin Barker_, Aug 10 2018
%e A221694 Some solutions for n=3:
%e A221694 ..2..1..1....0..2..1....1..1..0....1..2..0....2..1..0....1..0..0....0..2..1
%e A221694 ..0..0..2....1..0..2....3..0..1....0..3..0....0..3..0....1..3..1....2..1..0
%Y A221694 Cf. A221693.
%K A221694 nonn
%O A221694 1,2
%A A221694 _R. H. Hardin_, Jan 22 2013