A223647 - OEIS

%I #4 Mar 25 2013 07:28:15

%S 9,43,343,1973,10425,64669,347013,1639675,8731185,47326725,233731602,

%T 1110256634,5956720086,29392316077,153244540299,763311486416,

%U 3803535544870,19110083922981,96175235890299,476447020677810

%N Number of (n+2)X3 0..1 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 Column 3 of A223652

%H R. H. Hardin, <a href="/A223647/b223647.txt">Table of n, a(n) for n = 1..21</a>

%e Some solutions for n=3

%e ..1..1..1....1..1..1....1..0..1....1..0..0....1..1..1....1..0..1....1..0..0

%e ..0..0..1....1..1..1....0..0..0....1..1..1....0..0..0....1..1..1....1..0..0

%e ..1..0..0....0..0..0....0..0..0....0..0..0....0..0..1....0..0..0....0..0..0

%e ..1..0..0....1..0..0....0..0..1....1..0..0....0..0..0....1..0..0....1..0..0

%e ..1..0..0....1..0..1....1..1..1....1..1..1....1..1..1....1..1..1....1..1..1

%K nonn

%O 1,1

%A _R. H. Hardin_ Mar 25 2013