Recursive SQL

One of the most common school exercice about recursion is the factorial. Guess what, I am going to do it in sql with hierarchies!

I use the following ln property :
x1*...*xn = exp(ln(x1)+..+ln(xn)))

Ok, here it is

SQL> select n, (select exp(sum(ln(level))) from dual connect by level<=n) "N!" from t1;

N N!
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4 24
6 720