20210126, 05:50  #2 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
23143_{8} Posts 
Edited your message for coherence.
Don't expect it to happen every time. It's A033999, not A033998. 
20210127, 03:41  #3 
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.

20210127, 08:08  #4 
"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 
20210127, 15:02  #5 
6809 > 6502
"""""""""""""""""""
Aug 2003
101×103 Posts
3·11^{2}·29 Posts 

Thread Tools  
Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Is the work thread sequence match with cpu core sequence?  jiangv  Hardware  1  20200408 04:29 
Alternating Factorials  rogue  And now for something completely different  22  20171215 16:42 
Primes in nfibonacci sequence and nstep fibonacci sequence  sweety439  And now for something completely different  17  20170613 03:49 
Gay Marriage: weekly alternating viewpoints  BrianE  Soap Box  46  20081109 22:21 
Sequence  Citrix  Puzzles  5  20050914 23:33 