Let p be an odd prime number, and let n be a positive integer divisible by p. Show that $D_n$ has only one p-Sylow subgroup
I'm trying to prove this by saying np($D_n$) = ap+1 and a must be 0, but I'm stuck at the process of proving a have to be 0. How can I achieve it, thank you very much! (np(group G) means the number of p-Sylow subgroup in the group G)
It's solved, thanks to Arturo Magidin!