Hello hdb,

Brilliant use of vec, producing fast and very clever code. Bravo!

But — running your script on my system, I didn’t get anywhere near integer overflow before Windows effectively froze, with Task Manager showing memory at 97% and disk at 100%. (I didn’t time it, but it can’t have taken more than an hour or two to get to this point.) The console read:

2162984298      13994685375     1355    13994685375     1749335672
[download]

So then I ran my script to see if it would get that far. 14 hours and 37 minutes later (!) it had reached:

n = 2177458553, elapsed time: 52649.9s
[download]

with Task Manager showing memory at 60% and disk at 0%.

:-)

Cheers,