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Prime Spiral


The numbers arranged in a Spiral

\matrix{5 & 4 & 3\cr 6 & 1 & 2\cr 7 & 8 & 9\cr}

with Primes indicated in black, as first drawn by S. Ulam. Unexpected patterns of diagonal lines are apparent in such a plot, as illustrated in the above $199\times 199$ grid.


Dewdney, A. K. ``Computer Recreations: How to Pan for Primes in Numerical Gravel.'' Sci. Amer. 259, 120-123, July 1988.

Lane, C. ``Prime Spiral.''

mathematica.gif Weisstein, E. W. ``Prime Spiral.'' Mathematica notebook PrimeSpiral.m.

© 1996-9 Eric W. Weisstein