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Number of 4 X n binary matrices M with rows in strictly increasing order and rows of M*transpose(M) (mod 2) in strictly increasing order.
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%I #9 Feb 17 2024 21:08:20

%S 0,0,4,111,1793,32124,513260,8397376,133979600,2151884352,34376925632,

%T 550298217984,8799317537024,140789221362688,2252143151246336,

%U 36033204166164480,576491512426680320,9223724397701578752

%N Number of 4 X n binary matrices M with rows in strictly increasing order and rows of M*transpose(M) (mod 2) in strictly increasing order.

%H R. H. Hardin, <a href="/A181272/b181272.txt">Table of n, a(n) for n=1..27</a>

%e M and M*transpose(M) (mod 2) for 4 X 3:

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

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

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

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

%Y Row 4 of A181266.

%K nonn

%O 1,3

%A _R. H. Hardin_, Oct 10 2010