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

1, 3, 35, 792, 34547, 2902490, 468761578, 145469326676, 86673425993599

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