Each term of the series F12, I18, L24, O30 pairs a letter with a number. What is the term that follows O30?

Every number is twice the place of the letter beside it: F is at 6 and carries 12, I at 9 carries 18, L at 12 carries 24, O at 15 carries 30. The letters go on by three, so the next is at place 18, which is R, and its number is twice 18, that is 36. Adding 4 to the last number instead of doubling the new place gives R34 and adding 8 gives R38; advancing the letter by only two gives Q, whose doubled place is 34, so Q36 mixes the right number with the wrong letter.