A201721 Number of n X n 0..4 arrays with rows and columns lexicographically nondecreasing and no element equal to the number of horizontal and vertical neighbors equal to itself

4, 90, 19827, 56836178, 1692459595971, 545947219624185244

Offset

1,1

Comments

Diagonal of A201729

Links

Table of n, a(n) for n=1..6.

Example

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

Crossrefs

Sequence in context: A202918 A146506 A202575 * A374158 A195559 A195551

Adjacent sequences: A201718 A201719 A201720 * A201722 A201723 A201724

Keyword

nonn

Author

R. H. Hardin Dec 04 2011

Status

approved