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%I #3 Mar 20 2013 16:01:28
%S 28,784,5264,164650,3726450,89957891,2474370640,67279126908,
%T 1776982155124,53301717502997,1412061517830650,38566712740269981,
%U 1093842399226724212,31131482539555666716
%N Number of 3Xn 0..3 arrays with all rows having a nonnegative second derivative, and all and columns having a positive second derivative in a quadratic least squares fit, with one and two element arrays taken as having a zero second derivative
%C Row 1 of A223495
%e Some solutions for n=3
%e ..3..3..3....0..1..2....2..2..3....1..1..2....3..3..3....2..2..3....2..0..2
%e ..2..0..1....0..0..1....0..1..2....1..0..0....2..0..0....1..0..1....0..0..0
%e ..2..1..0....1..0..2....3..2..2....3..2..1....2..0..1....3..0..2....2..2..3
%K nonn
%O 1,1
%A _R. H. Hardin_ Mar 20 2013