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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A210906 Number of n X n 0..2 symmetric matrices with every element equal to zero or two horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order 0
1, 3, 20, 258, 5316, 175508, 9246604, 778330944, 104490906936, 22379344947816, 7640730937406288, 4158457819686881368, 3606450263851909019488 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..13.

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A331504 A197322 A197975 * A193194 A320945 A166232

Adjacent sequences:  A210903 A210904 A210905 * A210907 A210908 A210909

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 29 2012

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 October 23 14:42 EDT 2021. Contains 348214 sequences. (Running on oeis4.)