A single number, such as 21357, does not define a sequence.
If you mean: 9, 19, 39, 69 then the next number in the sequence is 109
81
22
121498
A single number, such as 21357, does not define a sequence.
A single number, such as 2481020, cannot define a sequence.
The next number is 0
A single number cannot define a sequence.
4
You are multiplying each number in the sequence by -2. Therefore, the next number in the sequence after 32 is -64.
Each following number in the sequence is being divided by 4. Therefore, the next number in the sequence is 3/4 = 0.75.
The next number is the sequence 236175969, 48, 12 is 236175861.
The next number in the sequence is 48.
If you mean: 9, 19, 39, 69 then the next number in the sequence is 109
8
81