(In reply to

Answer by K Sengupta)

Let the ith term of the given sequence be S(i).

Then, S(i) = smallest positive integer whose spelled out version

contain precisely (i+2) letters.

For example, the first term of the sequence is 1, which is spelled out as "one",which contains 3 letters. Therefore, S(1) = 3.

Similarly, S(2) = 4, since 4 is the smallest positive integer whose spelled out version contain precisely 4 letters.

We now observe that "twenty four" contains 10 letters and checking for the positive integers 1 to 24, we observe that 24 is indeed the smallest number with this property.

Thus, S(8) = 24

Similarly, checking for the numbers 1 to 23, we observe that the

word "twenty three" contains 11 letters, so that 23 is the smallest

positive integer with this property.

Therefore, S(9) = 23

Consequently, the required missing terms are 24 and 23.