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A223393 Number of 4Xn 0..2 arrays with all rows having a nonnegative second derivative, and all columns having a positive second derivative in a quadratic least squares fit, with one and two element arrays taken as having a zero second derivative 0
31, 961, 5450, 188958, 4182458, 101698908, 2972878486, 84155649292, 2392654352060, 83053389564196 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 2 of A223391

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

Some solutions for n=3

..2..0..2....0..0..1....2..1..2....2..2..2....2..0..1....2..2..2....2..1..0

..0..0..0....0..0..0....0..1..2....1..0..0....0..0..1....2..0..0....2..0..1

..2..0..1....1..0..0....2..0..0....2..0..1....1..0..0....0..0..0....0..0..0

..2..1..0....2..1..0....2..2..2....2..0..2....1..1..2....2..0..2....1..0..2

CROSSREFS

Sequence in context: A208693 A207563 A207418 * A207390 A207518 A207067

Adjacent sequences:  A223390 A223391 A223392 * A223394 A223395 A223396

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 19 2013

STATUS

approved

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Last modified May 22 09:40 EDT 2022. Contains 353941 sequences. (Running on oeis4.)