|
| |
|
|
A127503
|
|
Number of n X n matrices A with 1's on the main diagonal and -1's and 0's elsewhere such that A + A' has only 0's and -1's off the main diagonal and is positive semi-definite.
|
|
2
|
| |
|
|
|
OFFSET
|
1,2
|
|
|
COMMENTS
|
For number of different values of A + A' see A084553.
|
|
|
LINKS
|
Table of n, a(n) for n=1..9.
|
|
|
CROSSREFS
|
Cf. A085657, A085658, A080858, A083029, A038379, A127502.
Sequence in context: A199688 A098401 A011544 * A214363 A204821 A200903
Adjacent sequences: A127500 A127501 A127502 * A127504 A127505 A127506
|
|
|
KEYWORD
|
nonn,more,nice
|
|
|
AUTHOR
|
Max Alekseyev, Jan 16 2007
|
|
|
STATUS
|
approved
|
| |
|
|
