|
%I #6 May 04 2021 15:29:28
%S 4,25,139,773,4299,23909,132971,739525,4112907,22874149,127215787,
%T 707517317,3934894923,21884125925,121709722091,676895047237,
%U 3764587553931,20936952499621,116441967065899,647598149464325
%N Number of n X 3 0..1 arrays with every element equal to 0, 1 or 2 horizontally or antidiagonally adjacent elements, with upper left element zero.
%C Column 3 of A301841.
%H R. H. Hardin, <a href="/A301836/b301836.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 7*a(n-1) -8*a(n-2) for n > 3.
%e Some solutions for n=5
%e ..0..0..0. .0..1..0. .0..1..1. .0..1..0. .0..1..1. .0..0..1. .0..0..1
%e ..1..1..0. .1..1..1. .0..1..0. .1..0..0. .0..0..0. .1..0..0. .1..0..1
%e ..1..1..0. .0..0..1. .0..1..0. .1..1..0. .1..0..1. .1..0..0. .1..0..0
%e ..0..1..0. .1..0..1. .1..1..1. .0..1..0. .1..0..1. .1..0..0. .1..1..0
%e ..0..1..1. .1..0..1. .0..1..1. .1..1..1. .1..1..0. .1..0..1. .1..1..0
%Y Cf. A301841.
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 27 2018
| 