A118997 Number of real n X n symmetric (+1,-1) matrices with negative determinant.

1, 4, 16, 80, 8448, 907904, 81949952

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 * A337839 A001257 A133053

Adjacent sequences: A118994 A118995 A118996 * A118998 A118999 A119000

Keyword

nonn,more

Author

Giovanni Resta, May 08 2006

Status

approved