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!)
A206338 Number of (n+1) X 4 0..3 arrays with every 2 X 2 subblock having nonzero determinant and commuting with every horizontal or vertical neighbor. 1
455, 232, 1340, 682, 4007, 2030, 12005, 6074, 35999, 18206, 107983, 54606, 323937, 163806, 971799, 491406, 2915385, 1474206, 8746143, 4422606, 26238417, 13267806, 78715239, 39803406, 236145705, 119410206, 708437103, 358230606, 2125311297 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A206343.

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + 3*a(n-2) - 3*a(n-3) for n>12.

Empirical g.f.: x*(455 - 223*x - 257*x^2 + 11*x^3 + x^4 - 3*x^5 + 2*x^10 + 2*x^11) / ((1 - x)*(1 - 3*x^2)). - Colin Barker, Jun 15 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Cf. A206343.

Sequence in context: A092267 A232758 A284430 * A123563 A043475 A324633

Adjacent sequences:  A206335 A206336 A206337 * A206339 A206340 A206341

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 06 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 May 16 15:56 EDT 2022. Contains 353706 sequences. (Running on oeis4.)