

Largest accessible evenly divided motifs in (A) zeptomole-scale pools, and (B) SELEX-scale pools (602,000 and 1015 sequences, respectively). X-axis shows length of the sequence; y-axis shows largest motif accessible for each modularity at probability 0.5 (increasing the probability to 0.99 decreases the length of the accessible motif by at most two nucleotides in this range).










