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.

0, 0, 1, 1, 3, 25, 272, 4070, 79221, 1906501

Offset: 1

Author

N. J. A. Sloane, Sep 15 2013

Keywords

• nonn
• more

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

Cf. A229161, A229163, A229164, A000512

A column of A227061.

Extensions

a(10) from R. H. Hardin, Sep 17 2013