You can't google 9999999..99999999999999999999999

Can someone please explain me why that happens? Google says - "Our systems have detected unusual traffic from your computer network. Please try your request again later."

On a faintly related note, I once was calculating partitions, using a relatively inefficient method (memoization: if f(n,k) is the number of distinct ways to express n as the unordered sum of integers no greater than k, then f(n,k) = f(n-k,k) + f(n,k-1)). My computer started to feel the strain in the thousands (this algorithm is O(n^2) in space and time). I then googled for the partition of, say, 1034, which is:

  91363785902248291467082481888195

I figured that chances are that no website will have that integer on there by accident. Lo and behold, I found, among other results, a text file containing the partitions up to 10,000, presumably done with a more efficient algorithm (likely Euler's ridiculous pentagonal-number recurrence formula, which, memoized, is roughly O(n^1.5) in time and O(n) in space): http://oeis.org/A000041/b000041.txt

It seems to slow down, as you increase from:

111..111 11111..111111

and eventually crashes.

I'm guessing there is some kind of grammar parser breaking horribly. There's grammar parsers that have extremely poor performance trying to parse stuff that looks like this. It might do:

search 1 and 111111..11111

search 11 and 11111..11111

...

search 1 and 1 and 11111..111

...

...

...

and google detects that you are DOSing its server.

OK, someone else has pointed out that this is a range search, and google may be protecting CC searches.

100000..100000 Neither

The reason for this is that you can google ranges of numbers, and people a couple of years ago were using this feature to find credit card numbers that were posted online, eg searching for 4000000000000000..4999999999999999

It was around the time that johnny's google hacking page became popular, iirc. (http://www.hackersforcharity.org/ghdb/)