The next number in the sequence is... 64
125 (the sequence is successive numbers cubed)
64
Should there be a 16 in there somewhere? If so next three are 36, 49 and 64...
81
The next number will be 25 because 5 times 5 = 25
81
The next number in the sequence 2, 4, 16, 64 is 256.
The next number in the sequence is... 64
121
125 (the sequence is successive numbers cubed)
You are multiplying each number in the sequence by -2. Therefore, the next number in the sequence after 32 is -64.
49
144
64
64. It's the sequence f(n) = n^3
A single number, such as 256196144100643616 does not represent a sequence.