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A223496 Number of 3Xn 0..3 arrays with all rows having a nonnegative second derivative, and all and 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
28, 784, 5264, 164650, 3726450, 89957891, 2474370640, 67279126908, 1776982155124, 53301717502997, 1412061517830650, 38566712740269981, 1093842399226724212, 31131482539555666716 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 1 of A223495

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

Some solutions for n=3

..3..3..3....0..1..2....2..2..3....1..1..2....3..3..3....2..2..3....2..0..2

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

..2..1..0....1..0..2....3..2..2....3..2..1....2..0..1....3..0..2....2..2..3

CROSSREFS

Sequence in context: A208163 A207959 A267785 * A208043 A208032 A264368

Adjacent sequences: A223493 A223494 A223495 * A223497 A223498 A223499

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 20 2013

STATUS

approved

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Last modified November 28 20:13 EST 2022. Contains 358421 sequences. (Running on oeis4.)