Dear GAP-Forum,

Mario Pineda asked:

?can somebody tellme some references where I can find the imprimitive
groups of degree 18.

GAP contains lists of the transitive subgroups of S_n for degree up to 23.
(I computed these lists for my PhD thesis.). There are 983 groups of degree
18 (including the primitive ones). You can access them as:

TransitiveGroup(<deg>,<nr>);

there also is a selection function that can be used for example like:

AllTransitiveGroups(DegreeOperation,18,IsPrimitive,false,Size,[100..200]);

(Accessing the full list at once may take too much memory.)

I hope this is of help,

Alexander Hulpke