This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A000409 Singular n X n (0,1)-matrices: the number of n X n (0,1)-matrices having distinct, nonzero ordered rows, but having at least two equal columns or at least one zero column. (Formerly M4306 N1801) 6
 0, 6, 350, 43260, 14591171, 14657461469, 46173502811223, 474928141312623525, 16489412944755088235117, 1985178211854071817861662307, 846428472480689964807653763864449, 1299141117072945982773752362381072143359, 7268140170419155675761326840423792818571154945, 149650282980396792665043455999899697765782372693740287 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 COMMENTS This is a lower bound for the set of all n X n (0,1)-matrices having distinct, nonzero ordered rows and determinant 0 (compare A000410). Here ordered means that we take only one representative from the n! matrices obtained by all permutations of the distinct rows of an n X n matrix. a(n) is also the number of sets of n distinct nonzero (0,1)-vectors in R^n that do not span R^n. REFERENCES J. Kahn, J. Komlos, E. Szemeredi: On the probability that a random $\pm1$-matrix is singular, J. AMS 8 (1995), 223-240. J. Komlos, On the determinant of (0,1)-matrices, Studia Math. Hungarica 2 (1967), 7-21. N. Metropolis and P. R. Stein, On a class of (0,1) matrices with vanishing determinants, J. Combin. Theory, 3 (1967), 191-198. G. Kilibarda and V. Jovovic, "Enumeration of some classes of T_0-hypergraphs", in preparation, 2004. N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS FORMULA a(n) = -sum(stirling1(n+1, k+1)*binomial(2^k-1, n), k=0..n-1). a(n) = binomial(2^n-1, n) - A094000(n). - Vladeta Jovovic, Nov 27 2005 MAPLE with(combinat): T := proc(n) -sum(stirling1(n+1, k+1)*binomial(2^k-1, n), k=0..n-1); end proc: MATHEMATICA a[n_] := -Sum[ StirlingS1[n+1, k+1]*Binomial[2^k-1, n], {k, 0, n-1}]; Table[a[n], {n, 2, 15}] (* Jean-François Alcover, Nov 21 2012, from formula *) CROSSREFS Cf. A000410, A002884, A046747. Sequence in context: A289738 A211089 A221923 * A214445 A059415 A246112 Adjacent sequences:  A000406 A000407 A000408 * A000410 A000411 A000412 KEYWORD nonn,nice AUTHOR EXTENSIONS Edited by W. Edwin Clark, Nov 02 2003 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.