A208461 Number of n X n nonnegative integer arrays with new values 0 upwards 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, 20746, 10318694804, 4585512913250157737, 3787532222733253394267947322830, 10658767342117292737413813034097966371526603430

Offset

1,2

Links

Table of n, a(n) for n=1..7.

Example

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

Crossrefs

Diagonal of A208466.

Sequence in context: A212924 A068732 A174304 * A068939 A179106 A381267

Adjacent sequences: A208458 A208459 A208460 * A208462 A208463 A208464

Keyword

nonn,more

Author

R. H. Hardin, Feb 27 2012

Status

approved