

A247158


Number of binary n X n matrices in which each row or column sum is at most n/2.


10



1, 1, 7, 34, 7343, 304186, 1709852332, 702998475376, 94473463102448047, 417235486592360297626, 1273060578884483984898786092, 63478599188626680785194983697744, 4243780803142765740205701619107014789924
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OFFSET

0,3


LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..15
R. J. Mathar, The number of binary nXm matrices with at most k 1's in each row or column
E. Ordentlich, F. Parvaresh, R. M. Roth, Asymptotic enumeration of binary matrices with bounded row and column sums, SIAM J. Discrete Math. 26 (4) (2012) 15501575.
E. Ordentlich, F. Parvaresh, R. M. Roth, Asymptotic enumeration of binary matrices with bounded row and column weights, HPL2011239.


EXAMPLE

a(2)=7 counts the following 2 X 2 matrices: 1 matrix with all zeros, 4 matrices where a 1 is at any of the four corners, and 2 matrices with 1's covering a diagonal.


CROSSREFS

Cf. A197458, A283500.
Sequence in context: A027683 A196968 A000829 * A285802 A340523 A061825
Adjacent sequences: A247155 A247156 A247157 * A247159 A247160 A247161


KEYWORD

nonn


AUTHOR

R. J. Mathar, Nov 21 2014


EXTENSIONS

a(6)a(9) from Hiroaki Yamanouchi, Nov 22 2014
a(10)a(11) from Hiroaki Yamanouchi, Nov 26 2014
a(12) from Andrew Howroyd, May 31 2017


STATUS

approved



