6, 7, 7.5, 7.75
If we look, after the first two number, the next is gotten by adding half of the difference of the two numbers before to the last number.
6, 7
The next is:
7 - 6 = 1,
1/2 = 0.5
7 + 0.5 = 7.5 So the next is 7.5.
So we have 7 and 7.5
7.5 - 7 = 0.5
0.5/2 = 0.25
7.5 + 0.25 = 7.75
So if we have Tₓ, Tₓ₊₁,
So by observation, we can say the recursive formula is:
Tₓ₊₂ = Tₓ₊₁ + (Tₓ₊₁ - Tₓ)/2