We show that every n-vertex 5-connected planar triangulation has at most 9n-50 many cycles of length 5 for all n 20 and this upper bound is tight. We also show that for every k 6, there exists some constant C (k) such that for sufficiently large n, every n-vertex 5-connected planar graph has at most C (k) n^k/3 many cycles of length k. This upper bound is asymptotically tight for all k 6.
Agrahari et al. (Thu,) studied this question.