login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A230930 Number of black-square subarrays of (n+2) X (3+2) 0..3 arrays x(i,j) with each element diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 4, no adjacent elements equal, and upper left element zero. 1
8, 16, 102, 232, 1682, 3768, 27106, 60824, 437930, 982552, 7073698, 15870936, 114260634, 256361112, 1845635570, 4140964568, 29812290666, 66888415128, 481553712898, 1080439106264, 7778468998714, 17452180031640, 125644509294994 (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) = 16*a(n-2) + 3*a(n-4) - 10*a(n-6) + 24*a(n-8) - 16*a(n-10).

Empirical g.f.: 2*x*(4 + 8*x - 13*x^2 - 12*x^3 + 13*x^4 + 4*x^5 - 16*x^6 + 8*x^8) / (1 - 16*x^2 - 3*x^4 + 10*x^6 - 24*x^8 + 16*x^10). - Colin Barker, Sep 23 2018

EXAMPLE

Some solutions for n=4:

..x..0..x..0..x....x..0..x..0..x....x..0..x..0..x....x..0..x..0..x

..1..x..1..x..3....3..x..1..x..3....1..x..3..x..1....1..x..1..x..3

..x..2..x..0..x....x..0..x..2..x....x..2..x..2..x....x..2..x..0..x

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

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

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

CROSSREFS

Column 3 of A230935.

Sequence in context: A291001 A062508 A083086 * A080452 A270377 A264472

Adjacent sequences:  A230927 A230928 A230929 * A230931 A230932 A230933

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 01 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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 27 03:21 EDT 2020. Contains 337380 sequences. (Running on oeis4.)