|
%I #10 Apr 05 2020 21:41:21
%S 2,10,26,66,194,534,1468,4102,11402,31644,87958,244418,679050,1886836,
%T 5242786,14567272,40476178,112465998,312494040,868285644,2412590548,
%U 6703544510,18626248566,51754284540,143802757136,399565623778
%N Number of n X 3 binary arrays with each 1 adjacent to exactly two 0's.
%C Column 3 of A183335.
%H R. H. Hardin, <a href="/A183331/b183331.txt">Table of n, a(n) for n = 1..200</a>
%F Empirical: a(n) = 2*a(n-1) + a(n-2) + 3*a(n-3) + a(n-5) + 3*a(n-6) - a(n-7) - 3*a(n-8) - a(n-9).
%F Empirical g.f.: 2*x*(1 + 3*x + 2*x^2 - x^3 + 3*x^4 - 4*x^6 - 2*x^7) / (1 - 2*x - x^2 - 3*x^3 - x^5 - 3*x^6 + x^7 + 3*x^8 + x^9). - _Colin Barker_, Mar 27 2018
%e Some solutions for 4 X 3:
%e ..0..0..0....0..1..0....0..0..0....1..0..1....0..0..0....0..0..0....0..1..0
%e ..1..0..0....0..1..1....0..0..0....0..0..0....1..0..0....0..0..0....0..1..1
%e ..1..0..0....0..0..0....1..1..1....0..1..1....1..0..0....1..1..0....0..0..0
%e ..0..0..1....0..0..0....0..0..0....0..1..0....0..0..0....0..1..0....1..0..1
%Y Cf. A183335.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 03 2011
| 