| numero ample x y spirale tamponne|
x := y := ample := numero := 0.
tamponne := [ | item |
	numero := numero + 1.
	item := (spirale point: x@y) square; name: numero.
	numero isPrime ifFalse: [item color: Color blue]].

spirale := DrGeoCanvas new.
tamponne value.

4 timesRepeat:  [
	ample := ample + 1. 
	ample timesRepeat: [
		x := x + 1.
		tamponne value].
	ample timesRepeat: [
		y := y + 1.
		tamponne value].
	ample := ample + 1.
	ample timesRepeat: [
		x := x - 1.
		tamponne value].
	ample timesRepeat: [
		y := y - 1.
		tamponne value]]