Anna Uses the Letter X to Represent the Possible Sequences

Essay

Anna uses the letter X to represent the possible sequences of heads and tails that can be obtained when a coin is flipped three times. The possible sequences together with their probabilities are listed below:
$$\begin{array} { c | c } \mathrm { X } & \text { Probability of sequence } \mathrm { X } \\\hline \text { HHH } & 1 / 8 \\\text { HHT } & 1 / 8 \\\text { HTH } & 1 / 8 \\\text { HTT } & 1 / 8 \\\text { THH } & 1 / 8 \\\text { THT } & 1 / 8 \\\text { TTH } & 1 / 8 \\\text { TTT } & 1 / 8\end{array}$$
Is X a random variable? Why or why not? If it is not, which associated variable is a random variable? Give the probability distribution of the associated random variable.