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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A202796 Number of n X 2 binary arrays with every one adjacent to another one horizontally or vertically. 4
2, 10, 36, 126, 454, 1632, 5854, 21010, 75412, 270662, 971438, 3486624, 12513958, 44914250, 161203204, 578579694, 2076599286, 7453190368, 26750489166, 96011055010, 344596415668, 1236802258678, 4439047411742, 15932330156576 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A202802.

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) + a(n-2) + 4*a(n-3).

Empirical g.f.: 2*x*(1 + 2*x + 2*x^2) / (1 - 3*x - x^2 - 4*x^3). - Colin Barker, Feb 20 2018

EXAMPLE

Some solutions for n=5:

..0..1....0..0....0..1....1..0....0..0....1..0....1..1....0..1....0..1....1..0

..0..1....1..0....1..1....1..0....0..0....1..0....1..1....1..1....1..1....1..1

..1..1....1..1....1..1....1..1....0..1....0..0....1..0....0..0....1..0....0..1

..1..1....0..1....1..0....1..0....0..1....0..1....0..1....1..0....0..0....1..0

..1..0....1..1....1..0....1..0....0..0....0..1....1..1....1..1....0..0....1..0

CROSSREFS

Cf. A202802.

Sequence in context: A266942 A265844 A192858 * A001582 A026546 A256105

Adjacent sequences:  A202793 A202794 A202795 * A202797 A202798 A202799

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 24 2011

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 February 20 06:26 EST 2019. Contains 320332 sequences. (Running on oeis4.)