OFFSET
0,2
FORMULA
a(n) = (A059306(n)+(n+1)*(2*n+3))/4.
EXAMPLE
There are 5 binary singular matrices up to row and column permutation:
[0 0] [1 0] [1 1] [1 0] [1 1]
[0 0] [0 0] [0 0] [1 0] [1 1].
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladeta Jovovic, Sep 24 2001
EXTENSIONS
More terms from David Wasserman, Jul 16 2002
STATUS
approved