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A223656 Number of 6Xn 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 0
27, 729, 1973, 78213, 1044311, 22982345, 502081983, 9622736121, 218268103915, 6831466723781, 157202982490683, 3596007897529929 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 4 of A223652

LINKS

Table of n, a(n) for n=1..12.

EXAMPLE

Some solutions for n=3

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

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

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

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

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

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

CROSSREFS

Sequence in context: A218729 A171332 A097781 * A073537 A016947 A223790

Adjacent sequences:  A223653 A223654 A223655 * A223657 A223658 A223659

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 25 2013

STATUS

approved

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Last modified November 29 21:32 EST 2021. Contains 349416 sequences. (Running on oeis4.)