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 A223221 Number of nX2 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
 4, 16, 25, 121, 361, 1369, 4624, 18769, 68121, 299209, 1096209, 4347225, 17288964, 71961289, 271129156, 1103036944, 4381513249, 17397082404, 69668546704, 278284735729, 1102959947961, 4480296122241, 17736243719364, 70577657904601 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 2 of A223227 LINKS R. H. Hardin, Table of n, a(n) for n = 1..60 EXAMPLE Some solutions for n=3 ..0..1....0..0....0..0....1..0....1..1....0..1....1..1....0..1....0..1....1..0 ..0..1....0..0....0..0....1..0....1..0....0..0....1..0....0..0....0..1....1..0 ..0..1....0..0....0..1....1..0....1..0....0..0....1..1....1..0....1..1....1..1 CROSSREFS Sequence in context: A295921 A338406 A111350 * A210002 A105078 A050707 Adjacent sequences:  A223218 A223219 A223220 * A223222 A223223 A223224 KEYWORD nonn AUTHOR R. H. Hardin Mar 18 2013 STATUS approved

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Last modified April 14 12:11 EDT 2021. Contains 342949 sequences. (Running on oeis4.)