1 was excluded from primes through 20th century.
as a result, 1 became a number that is neither a prime nor a composite.
Why and how 1 was excluded from primes?
This video explains why and how.
#one #primenumber #mathhistory

different view of Goldbach and Euler about 1.
if 1 is included among primes, what will happen?
if 1 is excluded from primes, what will happen?
the fundamental theorem of arithmetic and 1 as a prime