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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A280279 Number of n X 1 0..2 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards. 5
0, 0, 1, 2, 8, 28, 94, 304, 960, 2976, 9096, 27488, 82304, 244544, 721888, 2119168, 6191104, 18011136, 52203648, 150809088, 434382848, 1247857664, 3576143360, 10226274304, 29184704512, 83138240512, 236438194176, 671370043392 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Column 1 of A280284.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 4*a(n-1) - 8*a(n-3) - 4*a(n-4) for n>7.

Empirical g.f.: x^3*(1 - 2*x + 4*x^3 + 2*x^4) / (1 - 2*x - 2*x^2)^2. - Colin Barker, Feb 19 2018

EXAMPLE

All solutions for n=4:

..0. .0

..1. .0

..1. .0

..1. .1

CROSSREFS

Cf. A280284.

Sequence in context: A178222 A090426 A279193 * A060995 A106731 A318010

Adjacent sequences:  A280276 A280277 A280278 * A280280 A280281 A280282

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 30 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 March 26 18:36 EDT 2019. Contains 321511 sequences. (Running on oeis4.)