Factorial into square... What???
Number Theory
Level
2
Let S be the sum of all values of n < 8 for which n!+1 is a perfect square.
P. S. Instead of using trial and error, i request you to find the solution :)
The answer is 16.
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Its called the Brocard's problem and so far there had been no known way to solve it. If someone solves it, I would love to see the solution. There are only three known numbers that satisfy this condition and they are all strictly less than 8