A193309 Number of n X n symmetric 0..3 arrays with no element equal to any horizontal or vertical neighbor, containing at least one 3 and with new values 0..3 introduced in lower triangular row major order

0, 0, 20, 1436, 175145, 47175440, 29471424170, 42983780102348, 146444614636063181, 1165528963228211645900, 21669813287663490052945610, 941174635410184709958677112920, 95492317441878724418372856301818197

Offset

1,3

Links

R. H. Hardin, Table of n, a(n) for n = 1..15

Example

Some solutions for 4X4
..0..1..0..1....0..1..3..0....0..1..3..1....0..1..2..0....0..1..3..1
..1..2..1..3....1..2..0..2....1..2..1..3....1..2..3..2....1..2..1..3
..0..1..0..2....3..0..3..0....3..1..0..2....2..3..2..3....3..1..2..1
..1..3..2..1....0..2..0..3....1..3..2..3....0..2..3..0....1..3..1..2

Crossrefs

Sequence in context: A177597 A127847 A363512 * A177601 A200900 A177603

Adjacent sequences: A193306 A193307 A193308 * A193310 A193311 A193312

Keyword

nonn

Author

R. H. Hardin Jul 22 2011

Status

approved