17. The numbers are being increased by odd numbers beginning with 3.
8
The sequence of number is 7.
174
266
It is (5+37)/2 = 21.
Assuming the space is between the 5 and the 37, you could put 21 in there and all the numbers would be 16 apart from each other.
17. The numbers are being increased by odd numbers beginning with 3.
8
The sequence of number is 7.
37.
174
57
36
266
If you meant: 31 37 41 43 47 53 then the next prime number is 59
Each number is the sum of the two numbers before it: 4+5=9, 9+5=14, 14+9=23, 23+14=37... The next number is 37+23=60