A223189 Number of nX2 0..2 arrays with all rows and columns having a nonnegative second derivative in a quadratic least squares fit, with one and two element arrays taken as having a zero second derivative

9, 81, 256, 2500, 19044, 149769, 1306449, 11573604, 98962704, 945378009, 8103240324, 71267107681, 649113816976, 5922783740329, 51729783444964, 469159715409025, 4214751562369924, 37759790203876225, 340491211679997504

Offset

1,1

Comments

Column 2 of A223195

Links

R. H. Hardin, Table of n, a(n) for n = 1..23

Example

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

Crossrefs

Sequence in context: A207020 A207364 A207786 * A207781 A207165 A208009

Adjacent sequences: A223186 A223187 A223188 * A223190 A223191 A223192

Keyword

nonn

Author

R. H. Hardin Mar 18 2013

Status

approved