The (double) Primorial sieve  &  Prime spirals E-mail

The  Modulo primality test  is based on the  prime spiral with one segment, as described in the  modulo primality test.pdf. Each natural number is member of the Eastward family of quadratic polynomials with only two terms.
Integers on the seam appear double, as per design.
By way of modular arithmetic the number of digits is reduced when checking a large integer for a possible divisor.
The modulo primality test can be used to factorize RSA-numbers.

The prime spiral with one segment is an offspring of the counterclockwise Ulam spiral with startvalue  0.
The Ulam spiral can be seen as an Ulam four-quarter spiral, and thus as a prime spiral with four segments.
There are infinitely many segmented prime spirals.
The full description is found in the document  segmented prime spirals.pdf.  

The  Ulam spiral (1963)  is named after the Polish mathematician  Stanislaw Ulam.
The graphical display shows that prime numbers have the tendency to appear on certain diagonals within the spiral, see also  the unraveling of the Ulam spiral.pdf.

Ing. J.I.M. (Hans) Dicker MEd.
The Netherlands

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    Please send a mail to:  info@primorial-sieve.com


Segmented prime spirals : Modulo primality test