Two different seeds producing the same 'random' sequence

Question

Maybe there is a very logic explanation for this, but I just can\'t seem to understand why the seeds 0 and 2,147,483,647 produce the same \"random\

Answer 1

Well, the reason will be connected with whatever derivation function is used by the Random class to derive a pseudo-random sequence from the seed. The real answer, therefore, is mathematical (and beyond my ability).

Indeed - I don't believe there's any guarantee that two different seeds will necessarily produce different sequences anyway.

Edit Okay - I'm going to do what bitbonk has done - but explain why:

public Random(int Seed)
{
    int num = (Seed == -2147483648) ? 2147483647 : Math.Abs(Seed);
    int num2 = 161803398 - num;
    this.SeedArray[55] = num2;
    int num3 = 1;
    for (int i = 1; i < 55; i++)
    {
        int num4 = 21 * i % 55;
        this.SeedArray[num4] = num3;
        num3 = num2 - num3;
        if (num3 < 0)
        {
            num3 += 2147483647;
        }
        num2 = this.SeedArray[num4];
    }
    for (int j = 1; j < 5; j++)
    {
        for (int k = 1; k < 56; k++)
        {
            this.SeedArray[k] -= this.SeedArray[1 + (k + 30) % 55];
            if (this.SeedArray[k] < 0)
            {
                this.SeedArray[k] += 2147483647;
            }
        }
    }
    this.inext = 0;
    this.inextp = 21;
    Seed = 1;
} 

We don't actually need to go too far into the code to see why - reading the code from top to bottom these are the values that will be stored by the above code when the seed is 0 and when the seed is 2147483647:

int num = (Seed == -2147483648) ? 2147483647 : Math.Abs(Seed);
  =>  num is 0 and 2147483647

int num2 = 161803398 - num;
  => num2 is 161803398 and -1985680249

this.SeedArray[55] = num2;
  => this.SeedArray is as above in both cases

int num3 = 1;
for (int i = 1; i < 55; i++)
{
  int num4 = 21 * i % 55
  this.SeedArray[num4] = num3;

  => num4 is 21, SeedArray[21] is 1

num3 = num2 - num3
  => num3 is 161803397 and -1985680250

if(num3 < 0)
  num3 += 2147483647

  => num3 is 161803397 and 161803397

After just the very first loop, algorithm has already converged for the two seed values.

Edit

As has been pointed out on the question - the sequences aren't the same - but they are clearly very very similar - and here we can see the reason for that similarity.