# Partitions contained in staircase shape

Let $\lambda_n=\{n-1,n-2,\dots,1\}$ be a partition of staircase shape. Let $f(n,k)=\#\{|\mu|=k|\mu\leq\lambda_n\}$ and $g(n,(i,j))=\#\{\mu|(i,j)\notin \mu,~\mu\leq \lambda_n\}$, where $(i,j)$ denotes the $(i,j)$ entry of the Ferrers diagram of $\lambda_n$. Can anyone give some references about $f(n,k)$ and $g(n,(i,j))$ or similar problems of contained partitions?

• For the first question, you are asking for an enumeration of Dyck paths by area. The generating function for this is known, but getting particular values might be a little messy. For the second problem, you can get a sum by adding the counts which pass through particular points. math.stackexchange.com/questions/64664/… I don't know whether the sum simplifies. – Douglas Zare Mar 24 '14 at 16:42
• Thanks very much for your comments and references, which are very helpful to me. – xmchenhit Mar 25 '14 at 1:16
• See my post [The number of partitions between two fixed partitions][1] [1]: mathoverflow.net/questions/161148/… – Harry Huang Apr 4 '14 at 4:48