I was thinking to use a dotplot to give a description of prime numbers. On Wolfram website there is written that each dotplot can be built by

    DotPlot[data_] := Module[{m = Tally[Sort[data]]},
    ListPlot[Flatten[Table[{#1, n}, {n, #2}] & @@@ m, 1], 
    Ticks -> {Automatic, Range[0, Max[m[[All, 2]]]]}]

I would like to have set of prime numbers on one axis and the natural numbers on the other one. Any idea? In addition, is it possible to realize a coprimality test by Dotplot (see figures below)? enter image description here enter image description here

In addition,

I often investigate on Ramanujan primes. Is it possible to apply this procedure to them? I think so but which is the condition I should use? I am trying from several days with no results. According to wolfram references, the basic code from them is the following:

         l = Table[PrimePi[x] - PrimePi[x/2], {x, 10^4}]; // Timing

         1 + Last[Position[l, #]][[1]] & /@ Range[0, 50]

These two simple lines provide the first 50 Ramanujan primes.

  • 4
    $\begingroup$ Why are you destroying questions you've posted? $\endgroup$
    – Kuba
    Mar 18, 2019 at 11:24
  • $\begingroup$ Because they are wrong! $\endgroup$
    – Spook82
    Mar 20, 2019 at 0:23
  • $\begingroup$ Questions are wrong? $\endgroup$
    – Kuba
    Mar 20, 2019 at 4:30

1 Answer 1


The code for DotPlot is a starting point that needs to be tailored (e.g., add or modify ListPlot options) for specific applications. It is not clear to me what you are asking for, so I have tailored DotPlot for displaying the prime factors of 50!

DotPlot[data_] := Module[{m = Tally[Sort[data]]},
  ListPlot[Flatten[Table[{#1, n}, {n, #2}] & @@@ m, 1],
   FrameTicks -> {Prime /@ Range[15], Range[0, Max[m[[All, 2]]], 4]},
   Frame -> {{True, False}, {True, False}},
   FrameLabel -> (Style[#, 14] & /@ {"Prime Factors", "Count"}),
   PlotRange -> All,
   PlotLabel -> Style["Prime Factors of 50!", 14, Bold]]]

data = Flatten[ConstantArray @@@ FactorInteger[50!]];


enter image description here

EDIT: For co-primes use CoprimeQ and display table with TableForm or ArrayPlot

 table = Table[Boole[CoprimeQ[m, n]], {m, 13}, {n, 13}],
 TableHeadings -> {Range[13], Range[13]}]

enter image description here

table == Table[Boole[GCD[m, n] == 1], {m, 13}, {n, 13}]

(* True *)

ArrayPlot[table, FrameTicks -> {Range[13], Range[13]}]

enter image description here


ArrayPlot[table, Mesh -> True, Frame -> True, 
 FrameTicks -> {Range[13], Range[13]}]

enter image description here

  • $\begingroup$ Thanks for your reply. As I see the code for dotplot provides several tools to investigate in prime numbers. Do you think that it is possible to use the same approach to plot a coprimality test? I mean, we could use a dot if the numbers are coprime and nothing otherwise. I have attached to figures of what I would like to plot in my first post. $\endgroup$
    – Spook82
    Dec 18, 2018 at 23:26
  • $\begingroup$ @Spook82 - Neither of your figures appear to have anything to do with a DotPlot. You might want to look at TableForm or Grid and ArrayPlot. $\endgroup$
    – Bob Hanlon
    Dec 18, 2018 at 23:39
  • $\begingroup$ Is it possible to realize them with these commands? Using the same structure of the code for Dotplot? $\endgroup$
    – Spook82
    Dec 19, 2018 at 0:49

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