A086906 - OEIS

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A086906

Number of symmetric singular n X n (0,1) matrices over the reals.

1, 4, 32, 496, 14172, 816684, 87982904 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Edwin Clark (eclark(AT)math.usf.edu) computed the first entries.`
	FORMULA	`a(n) = 2^(n*(n+1)/2) - A086899(n).`
	CROSSREFS	`Cf. A046747, A086899, A086879, A118989.` `Sequence in context: A192486 A037964 A089285 * 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 (g.resta(AT)iit.cnr.it), May 08 2006`

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Last modified February 13 12:30 EST 2012. Contains 205469 sequences.