The following function matches your list. It is, however, a wild guess of course as there is no way I can match it with the original program and I have no idea what these offsets mean.
private void getOffSet(byte one, byte two)
{
byte baseByte = 0x80;
int defaultOffset = 0x0418;
int mul = (one - baseByte) % 8;
int result = mul * 0x2000 + defaultOffset;
result += two * 0x0020;
Console.WriteLine(result.ToString("X"));
}