static List <PExp> Factor(BigInteger n)
{
List <PExp> pf = new List <PExp>();
BigInteger nn = n;
int e = 0;
while (!nn.BitTest(e))
{
e++;
}
if (e > 0)
{
nn = nn >> e;
pf.Add(new PExp(2, e));
}
BigInteger s = nn.Sqrt();
BigInteger d = 3;
while (nn > 1)
{
if (d > s)
{
d = nn;
}
e = 0;
while (true)
{
BigInteger div = BigInteger.DivRem(nn, d, out BigInteger rem);
if (rem.BitLength() > 0)
{
break;
}
nn = div;
e++;
}
if (e > 0)
{
pf.Add(new PExp(d, e));
s = nn.Sqrt();
}
d = d + 2;
}
return(pf);
}