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 A005019 (0,1)-matrices by 1-width. (Formerly M4461) 0
 1, 7, 169, 14911, 4925281, 6195974527, 30074093255809, 568640725896660991, 42170765737391337500161, 12325140160135610565932361727, 14244006984657003076298588475598849 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) is the number of ways to linearly order (with repetition allowed) n subsets of {1,2,...n} so that the generalized intersection of the subsets is not empty. [From Geoffrey Critzer, Mar 01 2009] a(n) is the number of n X n binary matrices with at least one row of 0's. [From Geoffrey Critzer, Dec 03 2009] REFERENCES Lam, Clement W. H. The distribution of \$1\$-widths of \$(0, 1)\$-matrices. Discrete Math. 20 (1977/78), no. 2, 109-122. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). Stanley, Enumerative Combinatorics, Volume I, Example 1.1.16 [From Geoffrey Critzer, Dec 03 2009] LINKS FORMULA a(n)=2^(n^2)-[(2^n)-1]^n [From Geoffrey Critzer, Mar 01 2009] EXAMPLE a(2)=7 because there are seven ways to order two subsets of {1,2} so that the intersection of the subsets contains at least one element: {1}{1};{1}{1,2};{2}{2};{2}{1,2};{1,2}{1};{1,2}{2};{1,2}{1,2} [From Geoffrey Critzer, Mar 01 2009] MATHEMATICA Table[2^(n^2) - (2^n - 1)^n, {n, 1, 15}] [From Geoffrey Critzer, Dec 03 2009] CROSSREFS a(n) = 2^(n^2)- A055601 [From Geoffrey Critzer, Dec 03 2009] Sequence in context: A258299 A012067 A012145 * A172027 A113562 A157203 Adjacent sequences:  A005016 A005017 A005018 * A005020 A005021 A005022 KEYWORD nonn AUTHOR EXTENSIONS Added a(7) Geoffrey Critzer, Mar 01 2009 More terms from Geoffrey Critzer, Dec 03 2009 STATUS approved

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Last modified January 19 16:27 EST 2019. Contains 319307 sequences. (Running on oeis4.)