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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 18 11:47 EDT 2022. Contains 356212 sequences. (Running on oeis4.)