Talk:Untouchable numbers

1464

Unfortunately, the factors of 14641 are {1,11,121,1331} which sum to 1464.
According to https://oeis.org/A005114/b005114.txt
There are 1212 not 1,216 untouchable numbers <= 10,000
There are 13,863 not 13,886 untouchable numbers <= 100,000 --Pete Lomax (talk) 08:50, 9 February 2021 (UTC)

Yes, I see that I need to extend the search for each range of untouchable numbers.   A fix (hopefully) will be forthcoming.   Thanks for finding those errors in the REXX's output.     -- Gerard Schildberger (talk) 09:00, 9 February 2021 (UTC)

That certainly slowed up the search when I extended the search field.     -- Gerard Schildberger (talk) 09:14, 9 February 2021 (UTC)

To match up to 1e5 I increased the limit to 18*n, a tactic I would deem rather unsound. Note added to the Phix entry. --Pete Lomax (talk) 09:17, 9 February 2021 (UTC)

reduction in the number of (counting) ranges

I've reduced the number of ranges for counting untouchable numbers.     It seems the upper limit for searching for touchable numbers was far higher than I guesstimated.     -- Gerard Schildberger (talk) 09:28, 9 February 2021 (UTC)

Number of untouchable numbers up to 1 million

According to one of the OEIS links there are 150,232 untouchable numbers up to 1e6 so it looks like the REXX result (150,233) is off by one here.

By running the Go program with a limit of 1e6 and a sieve factor of 20 (up from 14 for 1e5), I was in fact able to verify the figure of 150,232. Factors of 18 and 19 both gave 150,233 so there must be an 'awkward' number within this range which takes some eliminating. --PureFox (talk) 09:36, 11 February 2021 (UTC)