There are arbitrarily many pairs of integer sequences (of arbitrary origins) that coincide upto an $N$ but differ for an $n > N$. I assume, the coincidence will be considered accidentally then by default, but I may be mistaken about that.

One is disadviced to draw any conclusions from coincidences of integer sequences unless its proven, that they coincide for all $n$. (Even then there may be no sensible conclusions, as I have learned here: [Equivalence of families of objects with the same counting function][1].)

In any case, it is hard not to be entrapped to draw a conclusion when $N$ is very large. But what is "very large"? Thus my question:

> What is the largest $N$ with two known
> integer sequences coinciding upto $N$
> but differing for an $n > N$?

(Can this information be captured from OEIS by an intelligent query?)

**Edit**: To make things clear: I am aware of the fact that one can trivially define pairs of integer sequences which conincide for all $n$ but one single and aribitrarily large one. It should be clear that I am not interested in those.


  [1]: http://mathoverflow.net/questions/38551/equivalence-of-families-of-objects-with-the-same-counting-function/38592#38592