While not strictly in the same vein as O(n^10k), the constant factor in the proof that L=SL is 3^(2^65536) at the smallest. A lot of combinatorial problems can generate such algorithms, since they tend to rely on "we can solve this problem if this condition holds, we can make this condition hold for all inputs if we blow up our input with this large structure [which is technically constant time since the structure is fixed and not variant on size!]." Consider that this is the field of mathematics that produced a number that is "3 raised to itself so many times that I need to describe an algorithm just to write that number" that was used as the upper bound to a solution (the lower bound of which was 6).