Slightly Prime 2
Number Theory
Level
pending
If we define a slightly prime number is the number have exactly 3 factor not include itself, then how many slightly prime number have 3 digits?
The answer is 259.
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1 solution
The slightly prime number could be in two form, either product of two prime, or cube of a prime.
To count the first type, we first count the product of 2 and another prime (note that 2 x 2 is not satisfy). The total product of 2 is from 3 to 499, which are 80... Keep counting
Second type we have only 2 number, 125 and 343.