A192842 Number of n X n symmetric 0..3 arrays with each element equal to at least two horizontal or vertical neighbors, containing at least one 3 and with new values 0..3 introduced in lower triangular row major order.

0, 0, 0, 0, 0, 145, 6944, 635377, 69009813, 12541320254, 3495358855982, 1626847265319815, 1240274531663638765

Offset

1,6

Links

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

Example

Some solutions for 6X6
..0..0..0..0..0..0....0..0..1..1..3..3....0..0..1..1..2..2....0..0..0..0..2..2
..0..0..1..1..0..0....0..0..1..1..3..3....0..0..1..1..2..2....0..0..0..0..2..2
..0..1..1..1..2..2....1..1..2..2..3..3....1..1..1..1..1..1....0..0..0..1..1..1
..0..1..1..2..2..2....1..1..2..2..3..3....1..1..1..1..1..1....0..0..1..1..1..1
..0..0..2..2..3..3....3..3..3..3..3..3....2..2..1..1..3..3....2..2..1..1..3..3
..0..0..2..2..3..3....3..3..3..3..3..3....2..2..1..1..3..3....2..2..1..1..3..3

Crossrefs

Sequence in context: A008377 A076464 A018232 * A012813 A031612 A226849

Adjacent sequences: A192839 A192840 A192841 * A192843 A192844 A192845

Keyword

nonn

Author

R. H. Hardin, Jul 11 2011

Status

approved