login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 7 17:41 EST 2019. Contains 329847 sequences. (Running on oeis4.)