A223187 Number of n X n 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.

3, 81, 1138, 1133664, 3815358480, 103879396217927, 36869649918720635277

Offset

1,1

Comments

Diagonal of A223195.

Links

Table of n, a(n) for n=1..7.

Example

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

Crossrefs

Cf. A223195.

Sequence in context: A068562 A123656 A229842 * A060851 A116179 A379741

Adjacent sequences: A223184 A223185 A223186 * A223188 A223189 A223190

Keyword

nonn

Author

R. H. Hardin, Mar 18 2013

Status

approved