Question

What is the next number in the sequence 1, 121, 12321, 1234321, ... ?

Answer 1

1, 121, 12321, 1234321, 123454321, 12345654321, 123456764321, 123456787654321, 12345678987654321,

Answer 2

Here is the next numbers in the sequence:

1, 121, 12321, 1234321, 123454321, 12345654321, 123456764321, 123456787654321, 12345678987654321, etc.