Task

Write a program which counts up from   1,   displaying each number as the multiplication of its prime factors.

For the purpose of this task,   1   (unity)   may be shown as itself.



Example

      2   is prime,   so it would be shown as itself.

      6   is not prime;   it would be shown as   



2
×
3


{\displaystyle 2\times 3}

.
2144   is not prime;   it would be shown as   



2
×
2
×
2
×
2
×
2
×
67


{\displaystyle 2\times 2\times 2\times 2\times 2\times 67}

.



Related tasks

   prime decomposition
   factors of an integer
   Sieve of Eratosthenes
   primality by trial division
   factors of a Mersenne number
   trial factoring of a Mersenne number
   partition an integer X into N primes


using Primes, Printf
function strfactor(n::Integer)
    n > -2 || return "-1 × " * strfactor(-n)
    isprime(n) || n < 2 && return dec(n)
    f = factor(Vector{typeof(n)}, n)
    return join(f, " × ")
end
 
lo, hi = -4, 40
println("Factor print $lo to $hi:")
for n in lo:hi
    @printf("%5d = %s\n", n, strfactor(n))
end