A223219 Number of n X n 0..1 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

2, 16, 48, 3926, 278904, 137420222, 180758152704, 1113866774364638

Offset

1,1

Comments

Diagonal of A223227

Links

Table of n, a(n) for n=1..8.

Example

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

Crossrefs

Sequence in context: A192388 A162442 A159010 * A063721 A232209 A012180

Adjacent sequences: A223216 A223217 A223218 * A223220 A223221 A223222

Keyword

nonn

Author

R. H. Hardin Mar 18 2013

Status

approved