A210903 Number of n X n 0..2 symmetric matrices with every element equal to one, two or three horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order

0, 1, 4, 78, 3740, 449340, 133337482, 98375439948, 180233106621896, 820210662659082911, 9270740885407976025652, 260267690197125447266436984, 18148375825241525659505646969576

Offset

1,3

Links

Table of n, a(n) for n=1..13.

Example

Some solutions for n=4
..0..0..1..2....0..0..2..2....0..0..1..2....0..0..2..2....0..0..1..1
..0..0..1..2....0..1..1..2....0..0..1..2....0..1..1..1....0..0..1..0
..1..1..1..0....2..1..1..2....1..1..0..0....2..1..1..2....1..1..0..0
..2..2..0..0....2..2..2..2....2..2..0..0....2..1..2..2....1..0..0..0

Crossrefs

Sequence in context: A296997 A220240 A246606 * A054951 A215843 A374523

Adjacent sequences: A210900 A210901 A210902 * A210904 A210905 A210906

Keyword

nonn

Author

R. H. Hardin Mar 29 2012

Status

approved