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

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A221276 Number of 2Xn arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, with every occupancy equal to zero or two 1
0, 4, 4, 25, 52, 196, 520, 1681, 4840, 14884, 44044, 133225, 397852, 1196836, 3585040, 10764961, 32278480, 96864964, 290545684, 871725625, 2615029252, 7845353476, 23535617560, 70607649841, 211821620920, 635467254244, 1906397776924 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 2 of A221275

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..94

FORMULA

Empirical: a(n) = 4*a(n-1) -12*a(n-3) +9*a(n-4)

EXAMPLE

Some solutions for n=4

..0..0..0..2....0..2..2..0....2..2..2..0....2..0..0..0....0..2..2..0

..2..2..2..0....2..0..0..2....0..0..0..2....0..2..2..2....0..2..2..0

CROSSREFS

Sequence in context: A269152 A269097 A171633 * A117429 A132650 A112953

Adjacent sequences:  A221273 A221274 A221275 * A221277 A221278 A221279

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 09 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 14 21:33 EST 2017. Contains 296020 sequences.