The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A211052 1/3 the number of n X n 0..2 symmetric matrices with every element equal to one, two or three horizontal and vertical neighbors 1

%I #6 Dec 18 2015 18:18:07

%S 0,1,9,239,14669,2313041,915560157,915512113455,2309733753013069,

%T 14705975948890342013,236286306641789616616527,

%U 9580759647090339471565196845,980341335177418943590433413869387

%N 1/3 the number of n X n 0..2 symmetric matrices with every element equal to one, two or three horizontal and vertical neighbors

%H R. H. Hardin, <a href="/A211052/b211052.txt">Table of n, a(n) for n = 1..14</a>

%e Some solutions for n=4

%e ..0..0..1..0....1..1..2..2....1..1..0..0....2..2..0..2....0..0..1..1

%e ..0..1..1..0....1..1..2..1....1..1..1..1....2..2..0..2....0..0..2..2

%e ..1..1..1..1....2..2..1..1....0..1..1..0....0..0..2..2....1..2..2..2

%e ..0..0..1..1....2..1..1..1....0..1..0..0....2..2..2..2....1..2..2..2

%K nonn

%O 1,3

%A _R. H. Hardin_ Mar 30 2012

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 16 16:46 EDT 2024. Contains 373432 sequences. (Running on oeis4.)