If you find the difference between the numbers you'll see that if you add 2, 4, 8, 16,... you'll get that sequence!
E. g.
1 + 2 = 3
3 + 4 = 7
7 + 8 = 15
So I'll predict that to gt the next nunber, you'll need to add this to current number:
[tex] {2}^{n} [/tex]
Where n is just the position of the current number (1st, 2nd, 3rd). So the number after 31 should be:
[tex]31 + {2}^{5} = 63[/tex]
And the number after 63 should be:
[tex]63 + {2}^{6} = 127[/tex]
Now you try the last one! You can comment the answer and I'll check if it's right.