Harmonic and geometric progressions are distinct mathematical sequences, with harmonic progression defined as Tn = 1/n and geometric progression as Tn = a * r^n. The formula Tn = a + d(n-1) represents an arithmetic progression, not harmonic or geometric. The discussion highlights confusion regarding the classification of these sequences, with a mention of Gauss's work on arithmetic-geometric progressions, which possess unique mathematical properties. There is no established concept of arithmetic-harmonic progression in standard mathematics. Further clarification and examples are anticipated from participants in the discussion.