A210902 - OEIS

A210902

Number of n X n 0..2 symmetric matrices with every element equal to zero, two or three horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order

1, 3, 17, 252, 6328, 297609, 25886499, 4205102578, 1265408306700, 707818003940086, 733897633220152333, 1410044723992401143016

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..12.

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A322737 A376008 A201107 * A188803 A084040 A009495

Adjacent sequences: A210899 A210900 A210901 * A210903 A210904 A210905

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 29 2012

STATUS

approved