3 ms·
not always prime: try n=3 or n=5 or n=6 or n=7 or n=9 or n=10 or ... fun fact: all of these counterexamples have been divisible by 3 or 5.
by marvy 10y ago
not always prime: try n=3 or n=5 or n=6 or n=7 or n=9 or n=10 or ... fun fact: all of these counterexamples have been divisible by 3 or 5.