There is an entity which should replace the question mark in the sequence.
What character is the least probable to be a part of that entity?
The “F” is the least probable character.
The sequence features every 2nd day of a month. W – Wednesday, F – Friday, S – Sunday, T – Tuesday, T – Thursday, S – Saturday, M – Monday. The missing day is again Wednesday – W.
It is a little bit harder with the number though. In case the month consists of 31 days 1 should be written, in case the month consists of 30 days 2 should be written. Assuming that all numbers should be even (based on the nature of all the numbers in the sequence), 2 is more probable and suitable version.