G := 0.11111e-5*Re((-50000.*(-1.0182*R^18+8.9640*10^22-6.5799*10^21*R^3+4.0243*10^19*R^6+1.6412*10^18*R^9+13416.*sqrt(-1.*R^6*(3.6362*10^28*R^12+1.8565*10^10*R^21-7.9260*10^30*R^9-6.9380*10^18*R^15+5.9390*10^32*R^6+35821.*R^24+7.4270*10^16*R^18+1.8038*10^35-1.7654*10^34*R^3)))^(2/3)-1.0491*10^17*R^6-50601.*R^12+4.9005*10^18*R^3+2.0120*10^5*R^6*(-1.0182*R^18+8.9640*10^22-6.5799*10^21*R^3+4.0243*10^19*R^6+1.6412*10^18*R^9+13416.*sqrt(-1.*R^6*(3.6362*10^28*R^12+1.8565*10^10*R^21-7.9260*10^30*R^9-6.9380*10^18*R^15+5.9390*10^32*R^6+35821.*R^24+7.4270*10^16*R^18+1.8038*10^35-1.7654*10^34*R^3)))^(1/3)-1.0950*10^11*R^3*(-1.0182*R^18+8.9640*10^22-6.5799*10^21*R^3+4.0243*10^19*R^6+1.6412*10^18*R^9+13416.*sqrt(-1.*R^6*(3.6362*10^28*R^12+1.8565*10^10*R^21-7.9260*10^30*R^9-6.9380*10^18*R^15+5.9390*10^32*R^6+35821.*R^24+7.4270*10^16*R^18+1.8038*10^35-1.7654*10^34*R^3)))^(1/3)+4.4754*10^12*(-1.0182*R^18+8.9640*10^22-6.5799*10^21*R^3+4.0243*10^19*R^6+1.6412*10^18*R^9+13416.*sqrt(-1.*R^6*(3.6362*10^28*R^12+1.8565*10^10*R^21-7.9260*10^30*R^9-6.9380*10^18*R^15+5.9390*10^32*R^6+35821.*R^24+7.4270*10^16*R^18+1.8038*10^35-1.7654*10^34*R^3)))^(1/3)+(86605.*I)*(-1.0182*R^18+8.9640*10^22-6.5799*10^21*R^3+4.0243*10^19*R^6+1.6412*10^18*R^9+13416.*sqrt(-1.*R^6*(3.6362*10^28*R^12+1.8565*10^10*R^21-7.9260*10^30*R^9-6.9380*10^18*R^15+5.9390*10^32*R^6+35821.*R^24+7.4270*10^16*R^18+1.8038*10^35-1.7654*10^34*R^3)))^(2/3)-(1.8171*10^17*I)*R^6-(87648.*I)*R^12+(8.4882*10^18*I)*R^3-1.0015*10^20-1.7347*10^20*I)/(R^6*(-1.0182*R^18+8.9640*10^22-6.5799*10^21*R^3+4.0243*10^19*R^6+1.6412*10^18*R^9+13416.*sqrt(-1.*R^6*(3.6362*10^28*R^12+1.8565*10^10*R^21-7.9260*10^30*R^9-6.9380*10^18*R^15+5.9390*10^32*R^6+35821.*R^24+7.4270*10^16*R^18+1.8038*10^35-1.7654*10^34*R^3)))^(1/3)))

When I plot G from R=10..4000, y=-0.001..0.0001 I get a very smooth curve that looks like its C-infinity. It decays to 0 as R gets large. All I want to do is find out what this function can be approximated by (I see it as G ~ 0 + c1 (1/r) + c2 (1/r)^2 + c3(1/r) ^3 + O (1/r)^4
I've been using:
series(G, R = infinity)

Theoretically a function as smooth as this should have a series expansion of this form (I tried calculating it myself by doing the derivatives in maple but my laptop was running out of gas) , so I don't see why that command isn't returning the constants c1,c2,c3,etc.
I think it may have something to do with the fact that there's square roots of negative numbers in that expression .. but it shouldn't really be a problem .. the final result is actually real (the imaginary parts cancel out and whatevers left is numerical noise .. that's why I put the Re() at the beginning to filter out the imaginary-valued numerical noise).
Does anyone know a way around this ?? I've spent the last two days trying to do this and haven't got anywhere. I'd usually move on but this seems like a task that maple should be able to do. ANy help is very greatly appreciated