

A108185


Number of Cantorian n X n matrices over a 2letter alphabet.


0



0, 4, 24, 1744, 88480, 20785984, 4774925568, 3557583518976, 2784648830636544, 7054995406469377024, 16660711592693252288512
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OFFSET

1,2


COMMENTS

A matrix is Cantorian if no row matches any of the strings obtained by taking one term from each column in turn in such a way that they are from different rows. That is, no row word can match any transversal word.
More precisely, let the matrix be M = (M_ij). Then no row (M_i1, M_i2, ..., M_in) can agree with any "transversal" (M_{1, pi(1}}, ..., M_{n, pi{n}}) for any permutation pi in S_n.


LINKS



EXAMPLE

a(2) = 4 because the matrices [[a,a],[b,b]], [[a,b],[b,a]] and the matrices obtained by switching a with b are Cantorian.


CROSSREFS



KEYWORD

hard,nonn,nice


AUTHOR



STATUS

approved



