A086976 Number of monotonic matrices of order n.

2, 19, 712, 87685, 31102080, 28757840751

Offset

1,1

Comments

A monotonic matrix of order n is an n × N matrix in which every element is either 0 or contains a number from the set {1, 2, ..., n} subject to 3 conditions:

the filled-in entries in each row are strictly increasing;

the filled-in entries in each column are strictly decreasing;

for two filled-in cells with same entry, the one further right is higher (the positive slope condition).

See A070214 for more information.

Links

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

Eric Weisstein's World of Mathematics, Monotonic Matrix

Crossrefs

Cf. A070214.

Sequence in context: A290302 A278840 A300995 * A118189 A062623 A155956

Adjacent sequences: A086973 A086974 A086975 * A086977 A086978 A086979

Keyword

nonn,more

Author

Eric W. Weisstein, Jul 25 2003

Extensions

a(4) from Rob Pratt, Aug 23 2003

a(5)-a(6) from Giovanni Resta, Jul 28 2015

Status

approved