login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons 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 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A269188 Number of n X 2 0..3 arrays with some element plus some horizontally, diagonally, antidiagonally or vertically adjacent neighbor totalling three no more than once. 1
16, 108, 708, 4476, 27684, 168252, 1008804, 5983164, 35170980, 205214268, 1189853604, 6861684156, 39384946596, 225136169532, 1282284719268, 7279841963964, 41210177357988, 232678853273148, 1310648830057380 (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) = 10*a(n-1) - 21*a(n-2) - 20*a(n-3) - 4*a(n-4) for n>5.

Empirical g.f.: 4*x*(4 - 13*x - 9*x^2 - 4*x^3 + 4*x^4) / (1 - 5*x - 2*x^2)^2. - Colin Barker, Jan 19 2019

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 2 of A269194.

Sequence in context: A260357 A056001 A163725 * A165558 A337391 A250425

Adjacent sequences:  A269185 A269186 A269187 * A269189 A269190 A269191

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 20 2016

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 December 5 20:39 EST 2021. Contains 349558 sequences. (Running on oeis4.)