login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A208690 Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 1 1 and 1 0 1 vertically. 1
9, 81, 189, 927, 2889, 11727, 40581, 154359, 554733, 2062215, 7512453, 27700479, 101402109, 372809655, 1367107173, 5021003151, 18423673101, 67639822407, 248247487989, 911283026751, 3344800820445, 12277727839863, 45065827217925 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 4 of A208688.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = a(n-1) + 10*a(n-2) + 2*a(n-3) - 10*a(n-4).

Empirical g.f.: 9*x*(1 + 8*x + 2*x^2 - 10*x^3) / (1 - x - 10*x^2 - 2*x^3 + 10*x^4). - Colin Barker, Jul 05 2018

EXAMPLE

Some solutions for n=4:

..1..0..1..0....1..1..1..0....0..1..1..0....1..1..0..0....1..0..1..0

..1..1..1..0....1..0..1..1....0..1..0..0....1..1..1..0....1..0..1..0

..1..0..1..0....1..0..1..0....0..1..0..1....1..1..0..1....1..0..1..0

..1..0..1..0....1..0..1..0....0..1..0..0....0..1..0..0....0..1..1..0

CROSSREFS

Cf. A208688.

Sequence in context: A207489 A207886 A207731 * A207342 A207271 A207764

Adjacent sequences:  A208687 A208688 A208689 * A208691 A208692 A208693

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 01 2012

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 18 22:00 EDT 2022. Contains 353825 sequences. (Running on oeis4.)