A210904 - OEIS

A210904

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

1, 5, 108, 7722, 1640736, 1033777404, 1931855614272, 10707730229352132, 176032647122454516348, 8583448868806218541129800, 1241375815868250678950006865216, 532497522393110319522129344363284548

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

OFFSET

1,2

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..16

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS