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 A223406 T(n,k)=Number of nXk 0..3 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 4
 4, 16, 16, 36, 256, 36, 150, 1296, 1296, 150, 558, 22500, 11254, 22500, 558, 2126, 311364, 449810, 449810, 311364, 2126, 8480, 4519876, 13266784, 75789786, 13266784, 4519876, 8480, 33639, 71910400, 417523315, 8686866986, 8686866986 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Table starts ......4..........16...........36.............150..............558 .....16.........256.........1296...........22500...........311364 .....36........1296........11254..........449810.........13266784 ....150.......22500.......449810........75789786.......8686866986 ....558......311364.....13266784......8686866986....3454074121430 ...2126.....4519876....417523315...1075376609151.1516052461806611 ...8480....71910400..14781272688.158639905687500 ..33639..1131582321.521262156765 .131920.17402886400 .540025 LINKS R. H. Hardin, Table of n, a(n) for n = 1..58 EXAMPLE Some solutions for n=3 k=4 ..1..0..3..2....1..3..0..3....1..3..0..2....0..0..1..2....0..2..0..2 ..1..1..0..1....1..2..0..1....1..0..0..1....1..0..0..0....0..0..1..1 ..1..2..0..2....1..1..0..3....3..1..1..1....3..0..2..0....2..0..3..2 CROSSREFS Sequence in context: A341199 A072652 A058970 * A075382 A203252 A224064 Adjacent sequences:  A223403 A223404 A223405 * A223407 A223408 A223409 KEYWORD nonn,tabl AUTHOR R. H. Hardin Mar 20 2013 STATUS approved

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Last modified July 2 18:27 EDT 2022. Contains 355029 sequences. (Running on oeis4.)