(0,1) matrices with distinct rows and distinct columns

[Edwin Clark]

Yuval wrote:
> 
> Let me ask if there is a formula for a(n) where:
> a(n) = number of n X n (0,1) matrices with distinct rows and distinct 
> columns .
> 
> (or perhaps someone can compute a(n) ) .

Don't know about a formula, but here are the numbers for n from 1 to 5:

2,10,264,33864, 19158720

If we say that two matrices with distinct rows are equivalent if a
permutation of the rows takes one into the other, then there are n! 
in each equivalence class so the number of classes is:

2, 5, 44, 1411, 159656

(Actually this is the sequence I calculated. Then multiplying the nth term
by n! gives the first sequence.)

Check anyone?

--Edwin