A005020 The number of n X n (0,1)-matrices with a 1-width of 2. (Formerly M2182)

0, 2, 168, 32738, 20825760, 47942081642

Offset

1,2

Comments

Determining the 1-width of a matrix is NP-complete. - Sean A. Irvine, Mar 06 2020

References

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Table of n, a(n) for n=1..6.

Sean A. Irvine, Java program (github).

Clement W. H. Lam, The distribution of 1-widths of (0, 1)-matrices, Discrete Math. 20 (1977/78), no. 2, 109-122.

Index entries for sequences related to binary matrices.

Crossrefs

Sequence in context: A297407 A142602 A200042 * A157316 A007760 A230511

Adjacent sequences: A005017 A005018 A005019 * A005021 A005022 A005023

Keyword

nonn,more

Author

N. J. A. Sloane

Extensions

a(1) corrected and title improved by Sean A. Irvine, Mar 06 2020

Status

approved