login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A208079 Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 0 and 0 1 0 vertically. 1

%I

%S 9,81,441,2601,15129,88209,514089,2996361,17464041,101787921,

%T 593263449,3457792809,20153493369,117463167441,684625511241,

%U 3990289900041,23257113888969,135552393433809,790057246713849,4604791086849321

%N Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 0 and 0 1 0 vertically.

%C Row 4 of A208078.

%H R. H. Hardin, <a href="/A208079/b208079.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 5*a(n-1) + 5*a(n-2) - a(n-3).

%F Conjectures from _Colin Barker_, Jan 20 2018: (Start)

%F G.f.: 9*x*(1 + 4*x - x^2) / ((1 + x)*(1 - 6*x + x^2)).

%F a(n) = (9/4)*(2*(-1)^n + (3-2*sqrt(2))^n + (3+2*sqrt(2))^n).

%F (End)

%e Some solutions for n=4:

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

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 23 2012

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 19 22:05 EDT 2021. Contains 348095 sequences. (Running on oeis4.)