In C#:

class Solution {

static long getXor(long x)
{
    long n = x % 8;
    if (n == 0 || n == 1) return x;
    if (n == 2 || n == 3) return 2;
    if (n == 4 || n == 5) return x + 2;
    return 0;        
}

// Complete the xorSequence function below.
static long xorSequence(long l, long r) {
    return getXor(r) ^ getXor(l - 1);
}