[seqfan] Re: Ali Sada's A364054
Pontus von Brömssen
pontus.von.bromssen at gmail.com
Wed Oct 25 18:47:39 CEST 2023
Ali, the changed definition (starting at 3, allowing odd primes only) gives
the sequence A093933. It is finite, the last term being a(911) =
prime(911). The largest term along the way is a(783) = 437263 =
prime(36740).
Cheers,
Pontus
On Mon, Oct 23, 2023 at 7:42 AM Ali Sada via SeqFan <seqfan at list.seqfan.eu>
wrote:
> Thank you, Neil. I really appreciate it.
> If we change the definition to "a(1) = 3; for n > 1, a(n) is the least
> "odd prime" not already in the sequence such that a(n) == a(n-1) (mod
> prime(n-1))."
> This sequence might stop at one point when a(n) mod prime(n) = prime(n+1),
> given that prime(n+1) has not already appeared in the sequence. I would
> really appreciate it if someone could calculate more terms in this
> sequence. Maybe we will get lucky with a relatively small prime.
>
>
> 3, 5, 11, 31, 17, 61, 113, 79, 41, 179, 353, 43, 191, 109, 23,211, 317,
> 199, 443, 577, 151, 881, 1039, 541, 7, 977, 1381, 557, 1627, 101,
> 1231,1993, 421, 2339, 1783, 293, 3011, 499, 173, 3847, 733, 1091, 367,
> 2659, 2273, 1879,1481, 3169, 47, 1409, 1867, 2333, 3767, 2803, 1297, 269,
> 1321, 4549, 2381, 719,157, 1289, 4219, 2377, 2999, 1747, 479, 4451, 6473,
> 227, 3019, 1607, 3761, 1559,67, 1583, 3881, 769, 2357, 6367, 641, 4831,
> 3989, 9161, 1367, 4001, 457, 4049, 1307,4073, 2221, 5023, 233, 4129, 11003,
> 8009, 967, 4021, 10273, 859, 3023
>
> Best,
> Ali
>
>
> On Sunday, October 22, 2023 at 05:46:53 PM GMT+1, Neil Sloane <
> njasloane at gmail.com> wrote:
>
> The definition involves the primes, but otherwise this is quite similar to
> Recaman's A005132. However, the graph seems a bit simpler than Recaman's,
> since it appears to be dominated by pairs of straight lines, one descending
> and one ascending (as can be seen from Chai Wah Wu's b-file). 5 is still
> missing even after 10K terms. It would be nice to know more. (I added some
> comments to the entry.)
>
> Best regards
> Neil
>
> Neil J. A. Sloane, Chairman, OEIS Foundation.
> Also Visiting Scientist, Math. Dept., Rutgers University,
> Email: njasloane at gmail.com
>
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