

A175563


Number of n X n binary matrices that contain no 2 X 2 zero submatrix.


1



1, 2, 15, 334, 18521, 2293896, 586774783, 292184148320, 270280183791969, 447043237292379520, 1280479639717884356831, 6180626271969237488205312
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OFFSET

0,2


LINKS

Table of n, a(n) for n=0..11.


FORMULA

E.g.f.: the diagonal of exp( Sum_B x^lB * y^rB / Aut(B,lB,rB) ), where B runs over connected squarefree bipartite graphs with ordered bipartitions, (lB,rB) is the bipartition of B, and Aut(B,lB,rB) is the group of automorphisms of B preserving its bipartition.


CROSSREFS

Cf. A175564, A133791, A300749.
Sequence in context: A331344 A030642 A297077 * A231443 A068391 A215743
Adjacent sequences: A175560 A175561 A175562 * A175564 A175565 A175566


KEYWORD

hard,more,nonn


AUTHOR

Max Alekseyev, Jul 03 2010


EXTENSIONS

a(6)a(8) from Hiroaki Yamanouchi, Aug 27 2014
a(9)a(11) from Max Alekseyev, Feb 26 2022


STATUS

approved



