Mathematica Code For Finding Surjective Span 6 CA w/in a specific range:

Needs["KlausSutner`Automata`"];
data = Cases[
   Table[{r, ClassifyCA[CA[6, 2, r]]}, {r, 2^25, 2^32}], {x_, y_} /; 
    y > 0];
Export["~/Documents/surjective_span6.txt", data, "CSV"]