A223653 - OEIS

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

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Row 1 of A223652

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..38

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