A single number, such as 21357, does not define a sequence.
A
A
D20G
The sequence "rygb" represents the first letters of the colors in the rainbow: red, yellow, green, and blue. The next color in the sequence is indigo, which starts with the letter "i." Therefore, the next letter in the sequence is "i."
456789
A
A
It is: Y
p
D20G
K
Check out the link for the sequence.
L
h o n
040608
k comes next, and then l.
A single number, such as 2481020, cannot define a sequence.