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!)
A198900 Number of n X 2 0..4 arrays with values 0..4 introduced in row major order and no element equal to any horizontal or vertical neighbor. 5
1, 4, 33, 380, 4801, 62004, 804833, 10459180, 135958401, 1767426404, 22976444833, 298693487580, 3883014452801, 50479185229204, 656229400008033, 8530982176189580, 110902768218720001, 1441735986628126404 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A198906.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = 17*a(n-1) -55*a(n-2) +39*a(n-3).

Conjectures from Colin Barker, Feb 18 2018: (Start)

G.f.: x*(1 - 13*x + 20*x^2) / ((1 - x)*(1 - 3*x)*(1 - 13*x)).

a(n) = (26 + 13*3^n + 13^n) / 78.

(End)

EXAMPLE

Some solutions with values 0 to 4 for n=4:

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

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

..4..2....1..4....3..2....3..1....2..3....1..4....3..1....4..2....2..3....4..0

..2..4....3..2....4..3....2..4....4..2....4..3....4..2....2..0....4..0....0..3

CROSSREFS

Sequence in context: A208961 A113170 A187738 * A166906 A293020 A293193

Adjacent sequences:  A198897 A198898 A198899 * A198901 A198902 A198903

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 31 2011

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 October 7 05:27 EDT 2022. Contains 357270 sequences. (Running on oeis4.)