Alternating sequence

MattcAnderson · 2021-01-26, 05:18

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

Is in Online Encyclopedia of Integer Sequences
See

033999

Good fun

Batalov · 2021-01-26, 05:50

Edited your message for coherence.

Don't expect it to happen every time.

It's A033999, not A033998.

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:

Originally Posted by MattcAnderson

Also see a Numberphile video in YouTube
Called “How many ways can circles overlap?”

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.

2021-01-26, 05:18	#1
MattcAnderson "Matthew Anderson" Dec 2010 Oregon, USA 2115₈ Posts	Alternating sequence Just so you know- An alternating sequence A(n) = (-1)^n Is in Online Encyclopedia of Integer Sequences See 033999 Good fun

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2021-01-26, 05:50	#2
Batalov "Serge" Mar 2008 Phi(4,2^7658614+1)/2 23143₈ Posts	Edited your message for coherence. Don't expect it to happen every time. It's A033999, not A033998.

2021-01-27, 03:41	#3
CRGreathouse Aug 2006 3·1,993 Posts	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.

2021-01-27, 08:08	#4
MattcAnderson "Matthew Anderson" Dec 2010 Oregon, USA 3×367 Posts	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