Talk:Rare numbers: Difference between revisions
→21+ digit rare numbers: more 22s found
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There only seem to be 5 21 digit rare numbers, so I started looking at 22 digits. I found that each odd number of digits takes less time (about 80% of the time) of the previous even number of digits, but each even/odd pair (number of digits such as 16/17 vs 14/15) takes about 20 times a long as the previous pair, so the computation time increases dramatically for results above 19 digits. Here are a few found so far:
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119th (8,655,079,574,515,659,614,468)
(Provisionally numbered, not in final numeric order) This is probably about 50% of the search space. There may be many more to go. Lots of 2,2 combinations there so far. Nearly half of all rare numbers under 21 digits start and end with 2. I guess we will see if that trend continues as more solutions show up... --[[User:Enter your username|Enter your username]] ([[User talk:Enter your username|talk]]) 06:17, 2 December 2019 (UTC)▼
120th (8,655,079,374,155,679,614,468)
121st (8,045,841,654,642,561,594,308)
122nd (8,045,841,652,464,561,594,308)
123rd (8,655,059,576,513,659,814,468)
124th (8,655,059,772,157,639,814,468)</pre>
▲(Provisionally numbered, not in final numeric order) This is probably about
:Now that you've established that there are five 21 digit rare numbers, it might be worth mailing SSG (at guptass@rediffmail.com) to see if he'll add them to his list.
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