How can I use the DiscretePlot and LogPlot?


I am really new to mathematica and this will seem very basic, but the two last lines of the code do not work (the two prints work just fine), it gives me the error more input is needed(only for the DiscretePlot and LogPlot). The code is as follows:

iv1=a[0]==1; iv2=a[1]==1; rr=a[n]==a[n-1]+2*a[n-2]; sol=RSolve[{rr,iv1,iv2},a[n],n] // Simplify a[n_]=a[n]/.sol[[1]]; Print[a[2],"   ",a[3],"   ",a[4],"   ",a[5]] Print[a[50]] DiscretePlot[a[n],{n,1,20}] LogPlot[a[n],{n,1,20}]