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%I #4 Mar 18 2013 05:42:27
%S 9,81,256,2500,19044,149769,1306449,11573604,98962704,945378009,
%T 8103240324,71267107681,649113816976,5922783740329,51729783444964,
%U 469159715409025,4214751562369924,37759790203876225,340491211679997504
%N Number of nX2 0..2 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
%C Column 2 of A223195
%H R. H. Hardin, <a href="/A223189/b223189.txt">Table of n, a(n) for n = 1..23</a>
%e Some solutions for n=3
%e ..0..2....2..2....2..2....0..2....2..2....2..2....0..2....2..1....0..1....1..0
%e ..0..1....1..1....2..0....0..0....0..0....2..1....0..1....0..0....0..0....1..0
%e ..0..2....1..0....2..0....2..0....1..1....2..0....1..2....1..2....1..1....2..1
%K nonn
%O 1,1
%A _R. H. Hardin_ Mar 18 2013