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A223653 Number of 3Xn 0..1 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 1
3, 9, 9, 35, 77, 207, 513, 1415, 4009, 12499, 37577, 99863, 300723, 949821, 2565811, 7925175, 23158917, 68824353, 207493163, 617410067, 1841509697, 5611469021, 16589242023, 49212663699, 148570250829, 449163990819, 1326001156759 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 1 of A223652

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..38

EXAMPLE

Some solutions for n=3

..0..0..1....0..0..0....1..1..1....1..1..1....1..1..1....1..1..1....1..0..0

..0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0

..1..1..1....1..1..1....0..0..0....1..0..1....0..0..1....1..1..1....1..1..1

CROSSREFS

Sequence in context: A223576 A125824 A203558 * A238912 A038227 A080292

Adjacent sequences:  A223650 A223651 A223652 * A223654 A223655 A223656

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 25 2013

STATUS

approved

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Last modified September 18 01:39 EDT 2021. Contains 347504 sequences. (Running on oeis4.)