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A086906 Number of symmetric singular n X n (0,1) matrices over the reals. 4
1, 4, 32, 496, 14172, 816684, 87982904 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

W. Edwin Clark computed the first entries.

LINKS

Table of n, a(n) for n=1..7.

FORMULA

a(n) = 2^(n*(n+1)/2) - A086899(n).

CROSSREFS

Cf. A046747, A086899, A086879, A118989.

Sequence in context: A037964 A089285 A209197 * A034663 A192501 A192487

Adjacent sequences:  A086903 A086904 A086905 * A086907 A086908 A086909

KEYWORD

nonn

AUTHOR

Yuval Dekel (dekelyuval(AT)hotmail.com), Sep 19 2003

EXTENSIONS

a(6) and a(7) from Giovanni Resta, May 08 2006

STATUS

approved

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Last modified November 14 17:47 EST 2019. Contains 329126 sequences. (Running on oeis4.)