A005020 - OEIS

%I M2182 #18 Mar 06 2020 23:19:08

%S 0,2,168,32738,20825760,47942081642

%N The number of n X n (0,1)-matrices with a 1-width of 2.

%C Determining the 1-width of a matrix is NP-complete. - _Sean A. Irvine_, Mar 06 2020

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

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

%H Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a005/A005020.java">Java program</a> (github)

%H <a href="/index/Mat#binmat">Index entries for sequences related to binary matrices</a>

%K nonn

%O 1,2

%A _N. J. A. Sloane_

%E a(1) corrected and title improved by _Sean A. Irvine_, Mar 06 2020