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!)
A240631 Number of n X 3 0..1 arrays with no element equal to exactly three horizontal or vertical neighbors, with new values 0..1 introduced in row major order. 1
4, 25, 129, 637, 3147, 15590, 77269, 382933, 1897681, 9404215, 46603960, 230952833, 1144520961, 5671842895, 28107656217, 139291647132, 690280357055, 3420786394205, 16952212872439, 84009197931223, 416320004365162 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) + 4*a(n-2) + 2*a(n-3) + 7*a(n-4) + 6*a(n-5) - a(n-6) - a(n-7) - a(n-8).

Empirical g.f.: x*(4 + 9*x + 13*x^2 + 13*x^3 + 5*x^4 - 3*x^5 - 2*x^6 - x^7) / (1 - 4*x - 4*x^2 - 2*x^3 - 7*x^4 - 6*x^5 + x^6 + x^7 + x^8). - Colin Barker, Oct 29 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 3 of A240636.

Sequence in context: A240479 A317949 A263440 * A123660 A304842 A156701

Adjacent sequences:  A240628 A240629 A240630 * A240632 A240633 A240634

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 09 2014

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 September 25 16:53 EDT 2022. Contains 356986 sequences. (Running on oeis4.)