Frequency vector

I want to create a vecor with frequencies. 

I have tried this:

a <- c(1,1,1,1,2,3,4,5,5)
b <- table(a)
print (b[1])

which results in:

print (b[1])

1 
4 

The only thing I want is the 4.

So this seems obvious:
print (b[1,2])

but it does not work:
Error in b[1, 2] : incorrect number of dimensions

How do I get a vector or how do I refer to the "4" without getting the "1"
label as well?

View this message in context: http://www.nabble.com/Frequency-vector-tp18939882p18939882.html
Sent from the R help mailing list archive at Nabble.com.