A210923 Number of n X n 0..3 symmetric matrices with every element equal to zero, one or two horizontal and vertical neighbors, and new values 0..3 introduced in lower triangle row major order

1, 5, 166, 35207, 30211455, 99371076165, 1250065064815292, 60143467055359131310, 11066941546543240934864887, 7788436930452056534815427874703, 20963150916521213172749181596782816735

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n = 1..12

Example

Some solutions for n=4
..0..0..2..3....0..1..1..1....0..0..1..3....0..1..0..3....0..1..3..0
..0..1..0..2....1..0..2..3....0..0..1..2....1..2..2..0....1..2..2..0
..2..0..2..3....1..2..1..2....1..1..2..3....0..2..1..3....3..2..0..1
..3..2..3..2....1..3..2..3....3..2..3..0....3..0..3..0....0..0..1..0

Crossrefs

Sequence in context: A259613 A047940 A229414 * A229524 A288352 A301949

Adjacent sequences: A210920 A210921 A210922 * A210924 A210925 A210926

Keyword

nonn

Author

R. H. Hardin Mar 29 2012

Status

approved