O T T lol
CRC CBO and COL
It looks as if every third letter is an "r"; the remaining letters are in sequence.
R for Richard I - The letters are the first of the names of kings of England in the order of their reign.
There is very little information in the question to go on, but it looks like the next letter is R - an interval of five letters.
U (fourth, third, fourth, third, etc).
Traffic light sequence. Red, Red/Amber, Green, Amber, Red.
R, It is done on a number sequence 1, 5, 6, and 8 then reverse it 26, 21, 20 and 18, and R is the 18th letter of the alphabet. That is not CORRECT! V is the 22nd letter and U is the 21st letter, therefore the answer would be the letter S!
The next letter in the sequence would be W. Ex: E f g H i j k L m n o p Q r s t u v W.
It's the alphabet spaced by prime numbers: a+2=c, c+3=f, f+5=k, k+7=r, r+11 takes you past the end so start again at a = c.