A208401 Number of n X n 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors.

1, 15, 10682, 163422914, 39216100214432, 146298576850884166522, 8484183047877022205116428184, 7648479804732030712438650610523878146, 107185313935414834818609318544471943157967376388

Offset

1,2

Comments

Diagonal of A208408.

Links

R. H. Hardin, Table of n, a(n) for n = 1..13

Example

Some solutions for n=4
..0..1..1..2....0..0..0..1....0..1..0..0....0..1..1..0....0..0..1..0
..0..1..0..0....0..1..1..0....2..0..3..0....0..0..2..0....2..0..1..2
..0..0..3..0....0..1..1..0....2..0..3..1....0..2..1..1....1..3..0..0
..1..1..2..0....0..0..0..1....1..2..0..2....3..1..0..0....1..3..2..2

Crossrefs

Cf. A208408.

Sequence in context: A271403 A198720 A140285 * A198911 A207867 A206513

Adjacent sequences: A208398 A208399 A208400 * A208402 A208403 A208404

Keyword

nonn

Author

R. H. Hardin, Feb 26 2012

Status

approved