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-   -   Alternating sequence (https://www.mersenneforum.org/showthread.php?t=26443)

MattcAnderson 2021-01-26 05:18

Alternating sequence
 
Just so you know-
An alternating sequence
A(n) = (-1)^n

Is in Online Encyclopedia of Integer Sequences
See

[OEIS]033999[/OEIS]

Good fun

Batalov 2021-01-26 05:50

Edited your message for coherence.

Don't expect it to happen every time.

[SPOILER]It's A033999, not A033998.[/SPOILER]

CRGreathouse 2021-01-27 03:41

I think that's the only pure, nontrivial alternating sequence in the OEIS at the moment. There are A062157, A105812, A117154, A165326, and A280560 which alternate after some finite prefix, and of course A000004 which alternates in a trivial sort of way.

MattcAnderson 2021-01-27 08:08

Another interesting sequence is
OEIS.org/A250001
It is about “How many ways can circles overlap?”
Everyone is different.
Also see a Numberphile video in YouTube
Called “How many ways can circles overlap?”

The sequence has
1, 3, 14, 173 in the beginning

Cheers
Matt

Uncwilly 2021-01-27 15:02

[QUOTE=MattcAnderson;570213]Also see a Numberphile video in YouTube
Called “How many ways can circles overlap?”[/QUOTE]Was it too challenging for you to provide us with a link. The forum even has special mark-up for YT. Using it will provide for an embedded viewer.


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