OFFSET
0,3
COMMENTS
Off diagonal entries of an idempotent symmetric n X n (0,1)-matrix must be zero.
EXAMPLE
a(2) = 4 because [1,1] [0,1] [0,0] [1,0]
[0,0], [0,1], [1,1], [1,0], are non-symmetric and idemponent.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Torlach Rush, Jun 22 2020
STATUS
approved