[seqfan] Re: Name for a type of set needed

Bob Selcoe rselcoe at entouchonline.net
Mon Mar 27 14:26:01 CEST 2017

Hi Neil, Antii, and seqfans,

Antii - thanks for the insight, but still there's no name for these sets.  I 
said before:

> So for example, Column 6 is the set whose members have prime factors 
> {2,5}:
> {10, 20, 40, 50, 80, 100, 160, 200...}.
> Is there a standard name for such sets?

Maybe "squarefree root" sets?

Again, I think it's an important analytical tool so it's a bit surprising 
that there doesn't appear to be a conventional name for it - after all, we 
have "prime powers" for a given prime p, which is just a "squarefree root" 
set with p as its "root".

Neil - I suppose this isn't really the forum to create new conventional 
language to be used outside of OEIS, but is it OK to call them "squarefree 
root" sets for the purpose of submitting the transpose of A284311? (I'll 
submit it in between working on A280864 and my job, but should be fairly 


From: "Neil Sloane" <njasloane at gmail.com>
Sent: Monday, March 27, 2017 6:31 AM
To: "Sequence Fanatics Discussion list" <seqfan at list.seqfan.eu>
Subject: [seqfan] Re: Name for a type of set needed

> I agree with Antti that if we have a sequence
> obtained by reading an array by anti-diagonals
> upwards, we should also have the sequence we get by reading
> by anti-diagonals downwards
> (unless of course the array is symmetric).
> - the sequence for the transposed array, in other words.
> Bob (Selcoe), can you submit the companion sequence
> for the transpose of your A284311 ?
> Keep the entry simple, and just refer to A284311 for most of the 
> properties
> -----
> As can be seen, I have started a new message rather than
> simply replying to Antti's message.  That was because (bearing in
> mind what Olivier said) I wanted to keep this message short.
> Does anyone know if there is a way to tell Gmail not to include all the 
> earlier
> messages when you reply to a message?
> --
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