\input zb-basic \input zb-ioport \iteman{io-port 06118571} \itemau{de Mier, Anna; Noy, Marc} \itemti{On the maximum number of cycles in outerplanar and series-parallel graphs.} \itemso{Graphs Comb. 28, No. 2, 265-275 (2012).} \itemab Summary: Let $c(n)$ be the maximum number of cycles in an outerplanar graph with $n$ vertices. We show that $\lim c(n)^{1/n }$ exists and equals $\beta = 1.502837 \ldots$, where $\beta $ is a constant related to the recurrence ${x_{n+1} = 1 + x_n^2, \, x_0=1}$. The same result holds for the larger class of series-parallel graphs. \itemrv{~} \itemcc{} \itemut{cycles; outerplanar graph; series-parallel graph} \itemli{doi:10.1007/s00373-011-1039-9} \end