Which two numbers should replace the question marks?

Which two numbers should replace the question marks?


19, 20, 21, ?, ?, 26, 28, 32, 33, 40


 

Answer:

22 and 24: there are two interwoven sequences. Starting at 19, alternate numbers progress +2, +3, +4, +5. Starting at 20, alternate numbers progress +2, +4, +6, +8.