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A118990
Number of symmetric singular n X n (+1,-1) matrices over the reals.
2
0, 4, 32, 512, 15872, 907008, 104535552
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OFFSET
1,2
LINKS
Table of n, a(n) for n=1..7.
FORMULA
a(n) = 2^(n*(n+1)/2) -
A118994
(n) -
A118997
(n) [From
Max Alekseyev
, May 08 2009]
CROSSREFS
Cf.
A086906
,
A119010
,
A057982
,
A118992
.
Sequence in context:
A144935
A153511
A140179
*
A127945
A036442
A186339
Adjacent sequences:
A118987
A118988
A118989
*
A118991
A118992
A118993
KEYWORD
nonn
,
more
AUTHOR
Giovanni Resta
, May 08 2006
STATUS
approved
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Last modified April 23 20:33 EDT 2024. Contains 371916 sequences. (Running on oeis4.)