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This code gives me two sets of concentric circles with respective radii of 2n and 2n-1:

With[{n = 5}, Show[Graphics[
({{Circle[{0, 0}, 2*#1]}, {Circle[{0, 0}, 
     2*#1 - 1]}} & ) /@ Range[n]], Axes -> True]]

enter image description here

I would like alternating circles to be red and blue. I don't want to change anything else. But I can't figure out where to insert a PlotStyle instruction...

Any suggestions?

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With[{n = 5}, Graphics[{{Red, Circle[{0, 0}, 2*#1]}, Blue, {Circle[{0, 0}, 2*#1 - 1]}} &/@
  Range[n], Axes -> True]]

enter image description here

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  • $\begingroup$ Appreciated. Feeling a bit of muppet. Can't accept for 8 mins, but will then do so :-) $\endgroup$ – Richard Burke-Ward Oct 25 '18 at 23:23
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    $\begingroup$ @RichardBurke-Ward, it happens to all of us:) $\endgroup$ – kglr Oct 25 '18 at 23:24
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kglr's solution is what I would have done in old Mathematica. Nowadays, I would use Riffle[]:

With[{n = 5}, 
     Graphics[Riffle[Flatten[{Circle[{0, 0}, 2 #1 - 1], Circle[{0, 0}, 2 #1]} & /@ 
                             Range[n]], {Blue, Red}, {1, -2, 2}],
              Axes -> True]]

concentric circles with alternating colors

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