The Ulam spiral [La spirale d'Ulam].




Starting from the center of the picture -red square-, all the little squares (even the black ones) are numbered (N=1, 2, 3,...) when following a square spiral. The yellow squares display the first prime numbers ({2,3,5,7,11,13,17,19,23,29,31,37,41,...}).


See the generalized Ulam spiral:




See the 'N-twin' prime numbers (N=2,4,6,8):




[plus d'informations à propos de la spirale d'Ulam et de ses généralisations -en français/in french-]
[more information about the Ulam spiral and ist generalizations -in english/en anglais-]


(CMAP28 WWW site: this page was created on 04/01/2015 and last updated on 04/26/2015 12:25:04 -CEST-)



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Copyright (c) Jean-François Colonna, 2015.
Copyright (c) CMAP (Centre de Mathématiques APpliquées) UMR CNRS 7641 / Ecole Polytechnique, 2015.