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!)
A217268 Number of n X 3 arrays of occupancy after each element moves to some horizontal or vertical neighbor. 1
2, 64, 1472, 33856, 772800, 17640000, 402494400, 9183772224, 209543184576, 4781079618624, 109088244863424, 2489028863068224, 56791310102324928, 1295787666826276416, 29565538631067860928, 674586660240498844224 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 3 of A217273.
LINKS
FORMULA
Empirical: a(n) = 24*a(n-1) - 648*a(n-3) + 729*a(n-4) for n>5.
Empirical g.f.: 2*x*(1 + 8*x - 32*x^2 - 88*x^3 + 135*x^4) / ((1 - 24*x + 27*x^2)*(1 - 27*x^2)). - Colin Barker, Jul 23 2018
EXAMPLE
Some solutions for n=3:
..1..1..0....1..1..0....1..3..1....1..1..2....0..2..2....0..1..0....1..2..0
..2..0..1....0..1..1....1..0..0....2..0..0....0..0..0....1..2..3....1..1..1
..1..1..2....1..3..1....0..1..2....1..2..0....1..3..1....2..0..0....1..1..1
CROSSREFS
Cf. A217273.
Sequence in context: A047707 A223121 A134939 * A122603 A127691 A013822
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)