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%I #41 May 24 2018 15:56:18
%S 1,5,35,410,6178,122038,2921607,81609320,2588949454,91699869557,
%T 3582942335285,153048366545566,7096576775166579,355120233277118103,
%U 19084972486216897560,1096965038775477639368,67192642484367187943761,4372413334294007638726854
%N Number of nonisomorphic binary n X n matrices with three 1's per column under row and column permutations.
%H Andrew Howroyd, <a href="/A247596/b247596.txt">Table of n, a(n) for n = 3..40</a>
%H StackExchange, <a href="http://math.stackexchange.com/questions/616834/">How many arrays with crossed cells, order of rows/columns irrelevant</a>, Dec 13 2013
%p seq(matrix_marks(n,3), n=3..15); # Using the uploaded program to A247417
%o (PARI) \\ See A304942 for Blocks
%o a(n) = Blocks(n, n, 3); \\ _Andrew Howroyd_, May 23 2018
%Y Column k=3 of A304942.
%Y A diagonal of A305027.
%Y Cf. A247417, A247597, A247598.
%K nonn
%O 3,2
%A _Marko Riedel_, Sep 21 2014
%E Terms a(17) and beyond from _Andrew Howroyd_, May 23 2018