This puzzle reminds me of a conjecture made by Donald Knuth. I learned about it from the book "Artificial Intelligence" by Russel & Nordvig, and I quote it from there:
Knuth conjectured that, starting with the number 4, a sequence of factorial, square root, and floor operations will reach any desired positive integer. For example, we can reach 5 from 4 as follows:
Floor(Sqr(Sqr(Sqr(Sqr(Sqr((4!)!)))))) = 5
It would be nice to see if anyone could write 2011 using only one 4 and the mentioned functions!
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