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!)
A233077 Number of n X 3 0..3 arrays with no element x(i,j) adjacent to value 3-x(i,j) horizontally or antidiagonally, top left element zero, and 1 appearing before 2 in row major order. 1
5, 95, 1985, 41675, 875165, 18378455, 385947545, 8104898435, 170202867125, 3574260209615, 75059464401905, 1576248752439995, 33101223801239885, 695125699826037575, 14597639696346789065, 306550433623282570355 (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) = 22*a(n-1) - 21*a(n-2).

Conjectures from Colin Barker, Oct 07 2018: (Start)

G.f.: 5*x*(1 - 3*x) / ((1 - x)*(1 - 21*x)).

a(n) = (7 + 3^(1+n)*7^n) / 14.

(End)

EXAMPLE

Some solutions for n=4:

..0..1..3....0..1..0....0..1..1....0..0..1....0..0..0....0..1..1....0..0..0

..3..1..3....1..0..0....0..0..1....1..1..3....0..0..1....0..0..2....1..0..0

..0..1..3....0..2..3....2..0..1....0..1..0....2..3..3....2..3..1....0..1..1

..1..1..0....0..2..0....2..0..2....0..0..2....1..3..1....1..0..1....1..1..0

CROSSREFS

Column 3 of A233082.

Sequence in context: A116290 A274874 A275292 * A182960 A241998 A263394

Adjacent sequences:  A233074 A233075 A233076 * A233078 A233079 A233080

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 03 2013

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 June 30 03:34 EDT 2022. Contains 354913 sequences. (Running on oeis4.)