That's not a geometric sequence. g, 2g, 4g would be a geometric sequence with common ratio 2, and the next two terms would be 8g and 16g But having 1 for the first term keeps it from being a geometric sequence. If it were g/2, g, 2q, 4g then it would be a geometric sequence, with common ratio 2, and the next two terms would be 8g and 16g. But the first term cannot be 1. Do you copy it wrong? Edwin