Question 623187
The numbers are...
26, 6, 21, 1, 36, 16, 16, ...
If you take the numbers in pairs, like this...
(26, 6), (21, 1), (36, 16), (16, ?) you can see that the second number in each pair is the result of subtracting 20 from the first number of the pair.
So for the last pair, (16 - 20) = -4