The straight line connecting points < i2,-i> and < j2,j > (lying on the parabolla x=y2) crosses the x-axis at the point with of abscissa ij. Thus, if we connect all such points for i,j=2,3,..., then all composite numbers will be "crossed out" from the positive part of the axis of abscissas.
The first author suggested to use the above stated property of parabolla for constructing a nomogramm for multiplication in Kvant, 5(1971), p.25, ISSN 0130-2221. The idea to use it for visualization of prime numbers is due to the seconf author.
The above graphic files were produced by MATHEMATICA.
This paper was put on WWW on February 14, 1999.