login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A193810
Number of n X n symmetric 0..5 arrays with no element equal to the difference mod 6 of any two of its horizontal and vertical neighbors.
0
6, 109, 2785, 160273, 31474553, 21334488089, 46140355278097, 306619332905168069, 6168636777847547479765
OFFSET
1,1
EXAMPLE
Some solutions for 4 X 4:
..5..0..2..1....2..3..4..2....3..3..2..2....5..0..3..1....1..3..0..1
..0..4..1..2....3..4..3..3....3..1..3..3....0..2..0..0....3..1..0..3
..2..1..2..2....4..3..4..2....2..3..3..4....3..0..1..3....0..0..4..0
..1..2..2..3....2..3..2..3....2..3..4..2....1..0..3..5....1..3..0..1
CROSSREFS
Sequence in context: A337580 A288629 A041149 * A217987 A119814 A227443
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 05 2011
STATUS
approved