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%I #5 Dec 18 2015 18:18:29
%S 2,16,48,3926,278904,137420222,180758152704,1113866774364638
%N 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
%C Diagonal of A223227
%e Some solutions for n=3
%e ..1..0..1....1..0..1....0..0..0....1..0..1....0..0..1....1..0..0....1..1..1
%e ..1..0..0....0..0..1....0..0..0....1..0..0....0..0..0....0..0..0....1..0..0
%e ..1..0..0....0..0..1....0..0..1....1..0..1....1..0..1....1..1..1....1..0..1
%K nonn
%O 1,1
%A _R. H. Hardin_ Mar 18 2013
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