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A118991
Number of real n X n symmetric (0,1) matrices with nonzero permanent.
2
1, 5, 39, 753, 25887, 1842241, 247531775
OFFSET
1,2
FORMULA
a(n) = 2^(n(n+1)/2) - A118989(n) = 2^A000217(n) - A118989(n) = A006125(n+1) - A118989(n). [From Max Alekseyev, Apr 22 2010]
CROSSREFS
Sequence in context: A221412 A193118 A227636 * A253920 A156378 A220061
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