I am trying to understand the idea of annulus of convergence. This is the example I have been looking at but it has me completely stumped. [∞]\sum[/n=1] (z^n!)(1-sin(1/2n))^(n+1)! + [∞]\sum[/n=1] (2n)!/[((n!)^2)(z^3n)] All of the examples I have worked on in the past have been complex functions. This one seems odd because it is a Laurent Series.