login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A186874 Number of (n+2) X 4 0..3 arrays with every 3 X 3 subblock commuting with each horizontal and vertical neighbor 3 X 3 subblock. 1
2428, 421, 1201, 6829, 14221, 18517, 21661, 25381, 34645, 64384, 118027, 201190, 355210, 592102, 945346, 1600378, 2664955, 4328077, 7358623, 12328480, 20153704, 34046296, 56950552, 93410275, 157163740, 262861768, 432701869, 726100972 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A186881.

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) - a(n-2) + 3*a(n-3) - 6*a(n-4) + 3*a(n-5) + 3*a(n-6) - 3*a(n-7) for n>10.

Empirical g.f.: x*(2428 - 4435*x + 2787*x^2 - 2436*x^3 + 15069*x^4 - 11457*x^5 - 22980*x^6 + 1305*x^7 + 12492*x^8 + 7047*x^9) / ((1 - x)*(1 - x - 3*x^3 + 3*x^4 - 3*x^6)). - Colin Barker, Apr 19 2018

EXAMPLE

Some solutions for 6 X 4:

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

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

..0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0

..0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0

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

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

CROSSREFS

Cf. A186881.

Sequence in context: A257203 A156120 A078868 * A202201 A147984 A229871

Adjacent sequences:  A186871 A186872 A186873 * A186875 A186876 A186877

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 28 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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 18 01:19 EDT 2019. Contains 326059 sequences. (Running on oeis4.)