[seqfan] Re: conjectured list of divisibility sequences

[Richard Mathar]

http://list.seqfan.eu/pipermail/seqfan/2011-January/006814.html

ja> Date: Fri, 7 Jan 2011 16:52:34 +0100
ja> From: Joerg Arndt 
ja> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
ja> Subject: [seqfan] Re: conjectured list of divisibility sequences
ja> 
ja> And if so, don't forget to add the keyword "mult"  8-))

There are of course many divisibility sequences which are not multiplicative.

One example is A000079, where a(n)=2^n divides a(m)=2^m if n divides m,
but a(nm) =2^(n*m) is generally not a(n)*a(m) = 2^(n+m).

Another example is A001478, where a(n)=-n divides a(m)=-m if n divides m,
but a(nm) = -n*m is generally not a(n)*a(m) = +nm.