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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 0
2, 16, 48, 3926, 278904, 137420222, 180758152704, 1113866774364638 (list; graph; refs; listen; history; text; internal format)
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

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Last modified February 1 06:22 EST 2023. Contains 359981 sequences. (Running on oeis4.)