A192843 Number of n X n symmetric 0..4 arrays with each element equal to at least two horizontal or vertical neighbors, containing at least one 4 and with new values 0..4 introduced in lower triangular row major order

0, 0, 0, 0, 0, 21, 1640, 407889, 76204819, 26261341398, 12631545191076

Offset

1,6

Links

Table of n, a(n) for n=1..11.

Example

Some solutions for 6X6
..0..0..1..1..3..3....0..0..1..1..3..3....0..0..1..1..3..3....0..0..0..0..2..2
..0..0..1..1..3..3....0..0..1..1..3..3....0..0..1..1..3..3....0..0..0..0..2..2
..1..1..2..2..4..4....1..1..2..2..4..4....1..1..2..2..3..3....0..0..1..1..3..3
..1..1..2..2..4..4....1..1..2..2..4..4....1..1..2..2..3..3....0..0..1..1..3..3
..3..3..4..4..3..3....3..3..4..4..1..1....3..3..3..3..4..4....2..2..3..3..4..4
..3..3..4..4..3..3....3..3..4..4..1..1....3..3..3..3..4..4....2..2..3..3..4..4

Crossrefs

Sequence in context: A295414 A202800 A203361 * A130039 A221033 A221497

Adjacent sequences: A192840 A192841 A192842 * A192844 A192845 A192846

Keyword

nonn

Author

R. H. Hardin Jul 11 2011

Status

approved