login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A180752 Half the number of nX3 binary arrays with each element equal to at least two neighbors 1
0, 1, 1, 2, 3, 7, 14, 31, 67, 148, 325, 717, 1580, 3485, 7685, 16950, 37383, 82451, 181850, 401083, 884615, 1951080, 4303241, 9491097, 20933272, 46169785, 101830665, 224594602, 495358987, 1092548639, 2409691878, 5314742743 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Column 3 of A180760

LINKS

R. H. Hardin, Table of n, a(n) for n=1..99

FORMULA

Empirical: a(n) = 2*a(n-1) + a(n-2) - a(n-3) - a(n-5).

Empirical: G.f.: -x^2*(-1+x+x^3+x^2) / ( (x-1)*(1+x)*(x^3+2*x-1) ). a(n)-a(n-2) = A052980(n-3). - R. J. Mathar, Mar 24 2018

CROSSREFS

Sequence in context: A103421 A205484 A151530 * A000642 A348530 A229734

Adjacent sequences: A180749 A180750 A180751 * A180753 A180754 A180755

KEYWORD

nonn

AUTHOR

R. H. Hardin Sep 20 2010

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 December 4 02:16 EST 2022. Contains 358544 sequences. (Running on oeis4.)