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A118997 Number of real n X n symmetric (+1,-1) matrices with negative determinant. 3
1, 4, 16, 80, 8448, 907904, 81949952 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

a(2n+1) = A118994(2n+1) [From Max Alekseyev, May 08 2009]

CROSSREFS

Cf. A118999, A118994.

Sequence in context: A003471 A002777 A280923 * A001257 A133053 A110378

Adjacent sequences:  A118994 A118995 A118996 * A118998 A118999 A119000

KEYWORD

nonn,more

AUTHOR

Giovanni Resta, May 08 2006

STATUS

approved

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Last modified July 14 10:29 EDT 2020. Contains 335721 sequences. (Running on oeis4.)