A187671 Number of 3X3 0..n arrays with each 2X2 subblock nonsingular and the array of 2X2 subblock determinants symmetric about the diagonal and antidiagonal

24, 550, 4044, 17716, 56080, 150166, 336776, 702408, 1330728, 2385910, 3973400, 6550700, 10068336, 15247986, 22545648, 32579360, 45246528, 62983046, 84524916, 113900920, 150370548, 195521534, 249456396, 321513812, 404142192, 504603526

Offset

1,1

Comments

Row 2 of A187670

Links

R. H. Hardin, Table of n, a(n) for n = 1..31

Example

Some n=3 solutions for 3X3
..3..3..3....2..1..3....0..1..0....2..1..1....1..0..3....3..0..2....2..3..1
..0..1..0....2..0..2....2..1..2....2..2..0....0..3..2....0..1..2....1..0..1
..3..0..3....0..1..0....2..2..2....2..1..1....3..3..3....2..0..3....2..3..2

Crossrefs

Sequence in context: A192835 A235118 A223099 * A362357 A162810 A010561

Adjacent sequences: A187668 A187669 A187670 * A187672 A187673 A187674

Keyword

nonn

Author

R. H. Hardin Mar 12 2011

Status

approved