The missing number is 1.
The numbers in the sequence are all prime numbers, except for 1, which is not a prime number. Prime numbers are numbers that are only divisible by 1 and themselves. The first few prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, and 29.
The sequence starts with 2, which is the first prime number. The next number in the sequence is 3, which is the second prime number. The third number in the sequence is 5, which is the third prime number. The fourth number in the sequence is 7, which is the fourth prime number. The fifth number in the sequence is 11, which is the fifth prime number. The sixth number in the sequence is 13, which is the sixth prime number. The seventh number in the sequence is 17, which is the seventh prime number. The eighth number in the sequence is 19, which is the eighth prime number. The ninth number in the sequence is 23, which is the ninth prime number. The tenth number in the sequence is 29, which is the tenth prime number.
The sequence continues in this way, with each number being the next prime number after the previous number. However, the eleventh number in the sequence is not 31, which is the eleventh prime number. Instead, the eleventh number in the sequence is 1. This is because 1 is not a prime number.
Therefore, the missing number in the sequence is 1.