login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A198474 Number of 2n X 2 0..2 arrays with values 0..2 introduced in row major order and each element equal to an odd number of horizontal and vertical neighbors. 2
2, 12, 76, 492, 3212, 21036, 137932, 904812, 5936396, 38950572, 255572812, 1676946156, 11003350412, 72199015212, 473737530316, 3108453529452, 20396281280012, 133831275048876, 878140974959692, 5761968373855212 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A198477.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = 9*a(n-1) - 16*a(n-2).

Conjectures from Colin Barker, Mar 02 2018: (Start)

G.f.: 2*x*(1 - 3*x) / (1 - 9*x + 16*x^2).

a(n) = (2^(-4-n)*((9-sqrt(17))^n*(-5+3*sqrt(17)) + (9+sqrt(17))^n*(5+3*sqrt(17)))) / sqrt(17).

(End)

EXAMPLE

Some solutions for n=3:

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

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

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

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

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

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

CROSSREFS

Cf. A198477.

Sequence in context: A052875 A037725 A037620 * A285489 A121680 A277478

Adjacent sequences:  A198471 A198472 A198473 * A198475 A198476 A198477

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 25 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 January 22 07:30 EST 2020. Contains 331139 sequences. (Running on oeis4.)