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A229162
Number of n X n binary matrices with exactly 3 ones in each row and column, and with rows and columns in lexicographically nondecreasing order.
2
0, 0, 1, 1, 3, 25, 272, 4070, 79221, 1906501
OFFSET
1,5
REFERENCES
K. Yordzhev, On an Algorithm for Isomorphism-Free Generations of Combinatorial Objects, International Journal of Emerging Trends & Technology in Computer Science (IJETTCS), Web Site: www.ijettcs.org, Volume 2, Issue 6, November - December 2013, ISSN 2278-6856
LINKS
K. Yordzhev, Fibonacci sequence related to a combinatorial problem on binary matrices, arXiv preprint arXiv:1305.6790, 2013
K. Yordzhev, Semi-canonical binary matrices, arXiv preprint arXiv:1506.04642, 2015
CROSSREFS
A column of A227061.
Sequence in context: A080896 A126746 A118989 * A363354 A347255 A292111
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Sep 15 2013
EXTENSIONS
a(10) from R. H. Hardin, Sep 17 2013
STATUS
approved