A201980 Number of n X 7 0..3 arrays with rows and columns lexicographically nondecreasing read forwards and nonincreasing read backwards.

4, 420, 301612, 729771318, 1706069013928, 2238761872232964, 1716349328902123738

Offset

1,1

Comments

Column 7 of A201981.

Links

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

Example

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

Crossrefs

Cf. A201981.

Sequence in context: A215647 A228242 A036771 * A080321 A360844 A264469

Adjacent sequences: A201977 A201978 A201979 * A201981 A201982 A201983

Keyword

nonn

Author

R. H. Hardin, Dec 07 2011

Status

approved