Well...not exactly the same thing...I know...but the advertised size of the MAC Address Table (so Layer 2 <-> Port) is 64000 entries, this as reported on Tecnical Specifications of Aruba 3810 Switch Series QuickSpecs.
ARP Address Table size (so Layer 3 <-> Layer 2) - IMHO - could have a relationship with MAC Address Table sizeto with a rate of 1:3 or 1:2 at best (it's a guess...I know)...so, probably, we would expect an ARP Address Table's size varying between 20000/25000 entries and 32000 entries (at best).
As reference have a look here (numbers of ARP/MAC related to Aruba 5400R zl2), particularly Slides 10 and 24.
