Complete Search of Subgroup Defined by Edge Cubies

I recently completed a complete breadth-first search of the subgroup of the 3x3x3 cube defined only by the edge cubies. In other words, think of a cube where all the corner cubies are indistinguishable, and a state is defined only by the edge cubies. It took about 35 days on a dual-processor workstation, with three terabytes of disk storage. This was done without any use of symmetries. Here's the number of unique states at each depth:

0 1
1 18
2 243
3 3240
4 42807
5 555866
6 7070103
7 87801812
8 1050559626
9 11588911021
10 110409721989
11 552734197682
12 304786076626
13 330335518
14 248
Total 980995276800