A210933 - OEIS

A210933

Number of n X n 0..3 symmetric matrices with every element equal to zero, two, three or four horizontal and vertical neighbors, and new values 0..3 introduced in lower triangle row major order.

1, 3, 45, 2597, 404200, 158571061, 155381740144, 379683866415546, 2311350169900872167, 35031061332072915278464

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

Some solutions for n=4:

..0..1..3..1....0..1..2..0....0..1..0..1....0..1..2..1....0..1..3..2

..1..2..0..3....1..0..3..2....1..0..2..0....1..2..3..2....1..2..0..3

..3..0..3..0....2..3..2..0....0..2..0..2....2..3..0..3....3..0..2..0

..1..3..0..2....0..2..0..1....1..0..2..3....1..2..3..2....2..3..0..1

CROSSREFS

Sequence in context: A117253 A012833 A012747 * A356519 A027637 A228903

Adjacent sequences: A210930 A210931 A210932 * A210934 A210935 A210936

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 29 2012

EXTENSIONS

Name corrected by Andrew Howroyd, Mar 25 2025

STATUS

approved