Plot[LogIntegral[x] - PrimePi[x], {x,1,10000}]

ContourPlot[Log[Abs[Zeta[s + I t]]], 
   {t,0,40},{s,-7,5},
   Contours -> 50,
   ContourShading->False,
   PlotPoints->100,
   AspectRatio->.5]

Plot[RiemannSiegelZ[t], {t, 0, 110}]

Plot[RiemannSiegelZ[t], {t, 545439820, 545439830},
	PlotRange->All]