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A056990 Number of nonsingular n X n (-1,1)-matrices. 5
2, 8, 192, 22272, 11550720, 25629327360, 236229525504000, 8858686914082897920, 1331751782100764385607680 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..9.

Eric Weisstein's World of Mathematics, Nonsingular Matrix.

FORMULA

a(n) = 2^(2*n-1) * A055165(n-1).

CROSSREFS

Cf. A055165, A056989.

Sequence in context: A009505 A305737 A028368 * A234637 A234632 A070235

Adjacent sequences:  A056987 A056988 A056989 * A056991 A056992 A056993

KEYWORD

nonn,nice

AUTHOR

Eric W. Weisstein

EXTENSIONS

a(5) from Winston C. Yang (winston(AT)cs.wisc.edu), Aug 26 2000

a(6)-a(8) computed from A055165 by David desJardins (david(AT)desjardins.org), Apr 22 2001

a(9) from Max Alekseyev, computed from A055165, Jan 15 2007

STATUS

approved

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Last modified September 28 13:24 EDT 2020. Contains 337393 sequences. (Running on oeis4.)