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A223220 Number of nX1 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 1
2, 4, 5, 11, 19, 37, 68, 137, 261, 547, 1047, 2085, 4158, 8483, 16466, 33212, 66193, 131898, 263948, 527527, 1050219, 2116671, 4211442, 8401051, 16832288, 33765064, 67162966, 134559866, 269065487, 537669433, 1075891821, 2151469377, 4297450870 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A223227

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..122

EXAMPLE

All solutions for n=3

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

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

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

CROSSREFS

Sequence in context: A192581 A095023 A049913 * A113058 A066145 A095022

Adjacent sequences:  A223217 A223218 A223219 * A223221 A223222 A223223

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 18 2013

STATUS

approved

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Last modified July 20 05:43 EDT 2019. Contains 325168 sequences. (Running on oeis4.)