A202544 - OEIS

%I #6 Dec 18 2015 18:17:56

%S 1,2,18,1094,658492,5534917394,876480920594230,3399581643395993926522

%N Number of n X n nonnegative integer arrays with each row and column an ascent sequence (interior element no greater than one plus up-steps preceding it)

%C Diagonal of A202549

%e Some solutions for n=5

%e ..0..0..0..0..0....0..0..0..0..0....0..0..0..0..0....0..0..0..0..0

%e ..0..0..0..0..0....0..0..0..0..1....0..0..0..0..1....0..0..0..1..1

%e ..0..0..1..1..1....0..1..0..1..2....0..1..0..1..0....0..0..1..1..0

%e ..0..0..1..2..1....0..0..1..2..3....0..1..1..0..1....0..0..1..1..1

%e ..0..1..1..1..2....0..1..2..2..2....0..0..0..1..2....0..0..0..0..1

%K nonn

%O 1,2

%A _R. H. Hardin_ Dec 20 2011