A193269 Number of n X n symmetric 0..3 arrays with no element equal to any horizontal or vertical neighbor and with new values 0..3 introduced in lower triangular row major order

1, 2, 32, 1544, 176621, 47206184, 29472402866, 42983827798496, 146444618198769125, 1165528963636440929600, 21669813287735290595660642, 941174635410204103533009279920, 95492317441878732465782043745326917

Offset

1,2

Links

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

Example

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

Crossrefs

Sequence in context: A129348 A280211 A087084 * A088386 A329928 A093584

Adjacent sequences: A193266 A193267 A193268 * A193270 A193271 A193272

Keyword

nonn

Author

R. H. Hardin Jul 20 2011

Status

approved