As mentioned in the previous post, an alternative consists in finding the permutation of {1,…,N} by “adding” squares left and right until the permutation is complete or no solution is available. While this sounds like the dual of the initial solution, it brings a considerable improvement in computing time, as shown below. I thus redefined […]

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## Le Monde puzzle [#887bis]

November 16, 2014## Le Monde puzzle [#887]

November 15, 2014A simple combinatorics Le Monde mathematical puzzle: N is a golden number if the sequence {1,2,…,N} can be reordered so that the sum of any consecutive pair is a perfect square. What are the golden numbers between 1 and 25? Indeed, from an R programming point of view, all I have to do is to […]

## Le Monde puzzle [#882]

October 14, 2014A terrific Le Monde mathematical puzzle: All integers between 1 and n² are written in an (n,n) matrix under the constraint that two consecutive integers are adjacent (i.e. 15 and 13 are two of the four neighbours of 14). What is the maximal value for the sum of the diagonal of this matrix? Indeed, when considering […]

## Le Monde puzzle [#879]

September 21, 2014Here is the last week puzzle posted in Le Monde: Given an alphabet with 26 symbols, is it possible to create 27 different three-symbol words such that all symbols within a word are different all triplets of symbols are different there is no pair of words with a single common symbol Since there are 28x27x26/3×2=2925 […]

## Le Monde [short] guide to Vienna

September 16, 2014An interesting (?) coincidence: Le Monde weekend edition has its tourist page dedicated to Vienna! As usual, it is a list of places recommended by a local, Le Vienne de Robert Stadler, which includes Café Korb Postparkasse MAK (Museum für angewandte Kunst) Haus Wittgenstein Loos American Bar Maybe a wee bit limited a scope (albeit […]