

A223653


Number of 3Xn 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


1



3, 9, 9, 35, 77, 207, 513, 1415, 4009, 12499, 37577, 99863, 300723, 949821, 2565811, 7925175, 23158917, 68824353, 207493163, 617410067, 1841509697, 5611469021, 16589242023, 49212663699, 148570250829, 449163990819, 1326001156759
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OFFSET

1,1


COMMENTS



LINKS



EXAMPLE

Some solutions for n=3
..0..0..1....0..0..0....1..1..1....1..1..1....1..1..1....1..1..1....1..0..0
..0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0
..1..1..1....1..1..1....0..0..0....1..0..1....0..0..1....1..1..1....1..1..1


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



