What comes in place of question mark in the following series ? H3M, I…

H3M, I5N, L7O, Q9P, ?

So,

H -> +1 = I, I -> +3 = L, L -> +5 = Q, Q -> +7 = X

3 -> +2 = 5, 5 -> +2 = 7, 7 -> +2 = 9, 9 -> +2 = 11

M -> +1 = N, N -> +1 = O, O -> +1 = P, P -> +1 =Q

 

Thus, "X11Q" is correct.