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A210897 Number of (2n)X(2n) 0..2 symmetric matrices with every element equal to two horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order 0
1, 3, 35, 792, 34547, 2902490, 468761578, 145469326676, 86673425993599 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..9.

EXAMPLE

All solutions for n=2

..0..0..0..0....0..0..1..1....0..0..1..1

..0..1..1..0....0..0..1..1....0..0..1..1

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

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

CROSSREFS

Sequence in context: A093531 A129505 A185752 * A267221 A135516 A231644

Adjacent sequences:  A210894 A210895 A210896 * A210898 A210899 A210900

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 29 2012

STATUS

approved

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Last modified January 16 05:22 EST 2022. Contains 350374 sequences. (Running on oeis4.)