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 A118989 Number of symmetric n X n (0,1)-matrices over the reals with zero permanent. 2
 1, 3, 25, 271, 6881, 254911, 20903681 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..7. FORMULA a(n) = 2^(n*(n+1)/2) - A118991(n) = 2^A000217(n) - A118991(n) = A006125(n+1) - A118991(n). [From Max Alekseyev, Apr 22 2010] CROSSREFS Cf. A086906, A088672, A118991. Sequence in context: A009042 A080896 A126746 * A229162 A363354 A347255 Adjacent sequences: A118986 A118987 A118988 * A118990 A118991 A118992 KEYWORD nonn,more AUTHOR Giovanni Resta, May 08 2006 EXTENSIONS Max Alekseyev's formula corrected (the term 2^(n^2), counting the total number of binary matrices, has been substituted for 2*2^2*...*2^n = 2^(n(n+1)/2), the total number of binary symmetric matrices) by Herman Jamke (hermanjamke(AT)fastmail.fm), Sep 26 2010 STATUS approved

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Last modified May 20 01:45 EDT 2024. Contains 372703 sequences. (Running on oeis4.)