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Number of n X n 0..1 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly two mistakes.
0

%I #6 Apr 21 2020 12:54:28

%S 0,2,266,19750,1673658,251740932,90752836672,93037538287080,

%T 293564184229043556,2953569640505846392444

%N Number of n X n 0..1 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly two mistakes.

%C Diagonal of A278778.

%e Some solutions for n=4

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

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

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

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

%Y Cf. A278778.

%K nonn

%O 1,2

%A _R. H. Hardin_, Nov 28 2016