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A086976 Number of monotonic matrices of order n. 1

%I

%S 2,19,712,87685,31102080,28757840751

%N Number of monotonic matrices of order n.

%C 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:

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

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

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

%C See A070214 for more information.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/MonotonicMatrix.html">Monotonic Matrix</a>

%Y Cf. A070214.

%K nonn,more

%O 1,1

%A _Eric W. Weisstein_, Jul 25 2003

%E a(4) from _Rob Pratt_, Aug 23 2003

%E a(5)-a(6) from _Giovanni Resta_, Jul 28 2015

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Last modified August 5 19:54 EDT 2021. Contains 346488 sequences. (Running on oeis4.)