Sum digits of previous numbers algorithm in C#

I have sequence of numbers:
0, 1, 1, 2, 3, 5, 8, 13, 12, 7, 10…
Each number then is the sum of the separete digits of the previous elements.
It’s a bit like Fibonacci..
I want to write a function

int FindSimilarFibo(int x)
{
//x = 10 return 10
//x = 6  return 8
}

I wrote this, but I can’t figure out the correct algorithm:

int FindSimilarFibo(int x) {
    int p = 0;
    int q = 1;
    for (int i = 0; i < n; i++)
{
    int temp = p;
    p = q;
    q = temp + q;
    if (q > 9) 
    {
        int leftQ = q % 10;
        int rightQ = q / 10;
        q = leftQ + rightQ;
        q = temp + q;

    }
    if (p > 9)
    {
        int leftQ = q % 10;
        int rightQ = q / 10;
        temp = leftQ + rightQ;
        p = q;
        q = temp + q;
    }

}
    return p;
}

>Solution :

The problem looks to be that you’re overwriting previous values when computing the digits-sum of the next; so… don’t do that? perhaps:

static int FindSimilarFibo(int n)
{
    int p = 0;
    int q = 1;
    for (int i = 0; i < n; i++)
    {
        var next = SumDigits(p) + SumDigits(q);
        p = q;
        q = next;
    }
    return p;

    static int SumDigits(int value)
    {
        int sum = 0;
        while (value > 9)
        {
            sum += value % 10;
            value /= 10;
        }
        return sum + value;
    }
}