We get 2017 - Lycée Arago (Perpignan) Colegiul National B.P. Hasdeu (Buzau, Roumanie)

Titre du sujet
We get 2017
Établissement
Lycée Arago (Perpignan)
Année
2017-2018
Etablissement(s) jumelé(s)
Colegiul National B.P. Hasdeu (Buzau, Roumanie)
Résumé
At the beginning you only have an empty blackboard. At each step you can either write twice the number 1 on the blackboard or delete two numbers equal to n already written and replace them by n-1 and n+1.
How many steps at least will be necessary in order to reach the number 2017?
Mots clés