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!)
A208633 Number of n X 4 0..1 arrays with new values 0..1 introduced in row major order and no element equal to more than one of its immediate leftward or upward or right-upward antidiagonal neighbors. 1
8, 23, 71, 225, 722, 2331, 7548, 24476, 79423, 257807, 836973, 2717446, 8823199, 28648292, 93019712, 302032007, 980690055, 3184277945, 10339281402, 33571429395, 109005736508, 353939387572, 1149233948207, 3731539152111 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A208637.

LINKS

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

FORMULA

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

Empirical g.f.: x*(8 - 17*x + 4*x^2) / (1 - 5*x + 6*x^2 - x^3). - Colin Barker, Jul 05 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Cf. A208637.

Sequence in context: A241353 A059209 A099274 * A036562 A320310 A303720

Adjacent sequences:  A208630 A208631 A208632 * A208634 A208635 A208636

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 29 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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 5 14:29 EDT 2021. Contains 346469 sequences. (Running on oeis4.)