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A223219
Number of n X n 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
0
2, 16, 48, 3926, 278904, 137420222, 180758152704, 1113866774364638
OFFSET
1,1
COMMENTS
Diagonal of A223227
EXAMPLE
Some solutions for n=3
..1..0..1....1..0..1....0..0..0....1..0..1....0..0..1....1..0..0....1..1..1
..1..0..0....0..0..1....0..0..0....1..0..0....0..0..0....0..0..0....1..0..0
..1..0..0....0..0..1....0..0..1....1..0..1....1..0..1....1..1..1....1..0..1
CROSSREFS
Sequence in context: A192388 A162442 A159010 * A063721 A232209 A012180
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 18 2013
STATUS
approved