How to calculate the number of appearances and rounds of seven teams in a single knockout?

Round 1: 1-2 3-4 5-6 7 Bye.

Round 2: 1-3 2-5 4-7 6 Goodbye.

Round 3: 1-4 2-7 3-6 5 Goodbye.

Round 4: 1-5 2-6 3-7 4 Goodbye.

Round 5: 1-6 2-4 5-7 3 Goodbye.

Round 6: 1-7 3-5 4-6 2 Goodbye.

Round 7: 2-3 4-5 6-7 1 Goodbye

* * * Seven rounds, 2 1 field.