A183344 - OEIS

%I #8 Mar 27 2018 14:50:47

%S 1,7,9,17,33,59,109,201,369,679,1249,2297,4225,7771,14293,26289,48353,

%T 88935,163577,300865,553377,1017819,1872061,3443257,6333137,11648455,

%U 21424849,39406441,72479745,133311035,245197221,450988001,829496257

%N Number of n X 2 binary arrays with each 1 adjacent to exactly one 0 vertically and one 0 horizontally.

%C Column 2 of A183352.

%H R. H. Hardin, <a href="/A183344/b183344.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n) = a(n-1) + a(n-2) + a(n-3).

%F Empirical g.f.: x*(1 + 6*x + x^2) / (1 - x - x^2 - x^3). - _Colin Barker_, Mar 27 2018

%e Some solutions for 5 X 2:

%e ..0..1....0..0....0..0....0..0....0..1....0..0....0..0....1..0....0..0....1..0

%e ..0..0....0..0....0..0....1..0....0..0....1..0....1..0....0..0....0..0....0..0

%e ..1..0....0..0....1..0....1..0....0..1....1..0....1..0....0..1....0..0....1..0

%e ..1..0....0..0....1..0....0..0....0..1....0..0....0..0....0..1....0..0....1..0

%e ..0..1....0..1....0..1....0..0....0..0....0..1....1..0....1..0....1..0....0..0

%Y Cf. A183352.

%K nonn

%O 1,2

%A _R. H. Hardin_, Jan 04 2011