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A181344
Number of n X n matrices over {0,1} with rows and columns summing to 3, rows and columns sorted (>=) by value.
4
0, 0, 1, 1, 5, 25, 161, 1112, 8787, 76156, 728699, 7609065, 86162795, 1050755884, 13728407061, 191309852944
OFFSET
1,5
EXAMPLE
n=4: {1110,1101,1011,0111} is the only matrix where each row (column) - read as a binary number - is equal to or larger than the previous one, so a(4)=1.
CROSSREFS
KEYWORD
hard,more,nonn
AUTHOR
Michael Steyer (m.steyer(AT)osram.de), Oct 14 2010
EXTENSIONS
a(10)-a(16) from Bert Dobbelaere, Feb 23 2020
STATUS
approved