Thanks for catching a blatant error! I can see the error and the fix but I am more interested in what would allow you to do the same.
I’m on a bike tour right now, camping and visiting friends and family. Here’s my bike, the Invincible Summer, at Sancerre in the Loire valley.
Reached an APL colleague’s home in the Eifel yesterday and am tapping away this morning on an ancient netbook, but it’s no place to work. I’ll be back in London in a week or two. Assuming your need for primes is not urgent, how about we set up a tutorial session then online and I’ll coach you through identifying and fixing the error?
Please reply here or DM me at sjt@5jt.com if you would like that. (The offer is also open to anyone else who would like to join in.)