Abstract
We consider the number of spanning trees in a novel hybrid network created by inner-outer iteration. The hybrid network is small-world but not self-similar. Firstly, we introduce two particular electrically equivalent transformations: delta-edge transformation and Sierpinski-delta transformation. By using these two particular transformations, we find the changes of the conductances of corresponding electrically equivalent networks. Secondly, based on the inner-outer iteration structure characteristics, we obtain a closed-form formula for the number of spanning trees of the hybrid network, as well as its spanning tree entropy. Finally, we compare our result with those of previously investigated networks with the same average degree, and give an explanation for their differences.