How does Ulam's spiral appear if we map the integers before primality test?
Here I've used Euler's polynomial, and other than creating a dense map,
I don't see a striking pattern. However, you might be motivated to try
other transformations...I recommend to try verbs that map integers to
odd integers...
NB. run time 10 minutes for pixel resolution.
load 'viewmat'
r=:|.@:|:
s=:(,. (>:@:(>./)@:, + [: i. #))@:r
NB. Ulam=:1 :'2!:0''display ~/j64-802-user/temp/viewmat.bmp''[viewmat 1
p: u s ^:(360*2) i.1 1x'
Ulam=:1 :'viewmat 1 p: u s ^:(360*2) i.1 1x'
41 1 1x&p.Ulam''
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