A227636 - OEIS

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A227636

Number of n X n 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X(n+1) binary array having determinant equal to one, with rows and columns of the latter in nondecreasing lexicographic order

%I #5 Dec 18 2015 18:18:38

%S 1,5,39,667,25241,2139328,420651813,196026480660

%N Number of n X n 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X(n+1) binary array having determinant equal to one, with rows and columns of the latter in nondecreasing lexicographic order

%C Diagonal of A227641

%e Some solutions for n=4

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

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

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

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

%K nonn

%O 1,2

%A _R. H. Hardin_ Jul 18 2013