Le Monde puzzle [#6]

February 17, 2011

(This article was first published on Xi'an's Og » R, and kindly contributed to R-bloggers)

A simple challenge in Le Monde this week: find the group of four primes such that any sum of three terms in the group is prime and the overall sum is minimised. Here is a quick exploration by simulation, using the schoolmath package (with its imperfections):


for (t in 1:10^4){

 for (j in 2:4)

 if ((sto)&(sum(B)

providing the solution 5 7 17 19.

A subsidiary question in the same puzzle is whether or not it is possible to find a group of five primes such that any sum of three terms is still prime. Running the above program with the proper substitutions of 4 by 5 does not produce any solution, even when increasing the upper boundary in A. So it is most likely that the answer is no.

Filed under: R, Statistics Tagged: bug, Le Monde, mathematical puzzle, prime numbers, schoolmath

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