[R] Latex problem in Rd file

[William H. Asquith]

I am trying to build

\deqn{(  \begin{array}{c}
               k-1 \\
                j
          \end{array}  )
      }

To represent the combinatorial notation as in

   k-1
    j

but R is rendering PDF literally as follows

( k-1\j )

which is not correct. This is happening on Linux and MacOSX 
installations.

I have tried variations of the \deqn{} to no avail.
Any suggestions or point me to an existing package with an Rd file that 
has and latex array in it.

Thanks
-wa