A223188 Number of n X 1 0..2 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.

3, 9, 16, 50, 138, 387, 1143, 3402, 9948, 30747, 90018, 266959, 805676, 2433677, 7192342, 21660095, 64921118, 194318785, 583516248, 1749692999, 5235795129, 15779920510, 47191559739, 141322913448, 424521847845, 1275708336588

Offset

1,1

Comments

Column 1 of A223195.

Links

R. H. Hardin, Table of n, a(n) for n = 1..83

Example

All solutions for n=3
..1....1....2....0....2....1....2....0....2....2....0....1....2....0....2....1
..1....0....0....0....0....0....2....0....1....0....1....0....1....0....1....1
..2....1....2....1....1....0....2....2....0....0....2....2....1....0....2....1

Crossrefs

Cf. A223195.

Sequence in context: A058538 A197531 A117108 * A145796 A056403 A181349

Adjacent sequences: A223185 A223186 A223187 * A223189 A223190 A223191

Keyword

nonn

Author

R. H. Hardin, Mar 18 2013

Status

approved