The large value for the 6-palindrome case, a(6)=2853326516320, has 139 as the smallest of the three bases.
Coincidentally, the following much shorter term, a(7)= 3360633, involves base 9 through 11, the conjunction of base-9 and base-10 palindromes (
A029965) comes up a term short (assuming space limitations remain as they are at the beginning of 2011), and
A053740 is a totally unrelated collection of palindromes that also contains 33633.
