A140907 Number of 3 X 7 matrices with elements in 0..n with each row and each column in nondecreasing order. 3,7,n can be permuted, see formula.

1, 120, 4950, 108900, 1557270, 16195608, 131589315, 877262100, 4971151900, 24584605760, 108284013552, 431621592480, 1577078895600, 5337805492800, 16880809870980, 50245234086564, 141622596077325, 379998709805000, 974996689631250, 2401570793407500

Offset

0,2

Links

Table of n, a(n) for n=0..19.

Formula

(empirical) set p,q,r to n,7,3 (in any order) in s=p+q+r-1; a(n) = product {i in 0..r-1} (binomial(s,p+i)*i!/(s-i)^(r-i-1))

Crossrefs

Sequence in context: A283344 A223754 A174686 * A072419 A246193 A246613

Adjacent sequences: A140904 A140905 A140906 * A140908 A140909 A140910

Keyword

nonn

Author

R. H. Hardin, Jul 05 2008

Status

approved