[seqfan] Re: Canonical bijection from positive integers to positive rationals.

Frank Adams-watters franktaw at netscape.net
Tue Mar 3 16:46:50 CET 2020


This ought to be in the index, I would think.

Franklin T. Adams-Watters


-----Original Message-----
From: Peter Munn <techsubs at pearceneptune.co.uk>
To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
Sent: Tue, Mar 3, 2020 9:17 am
Subject: [seqfan] Re: Canonical bijection from positive integers to positive rationals.

Update: Having found another nice bijection in A229994(n)/A077610(n), I
have listed this and others mentioned in this thread in the crossrefs for
A071974.

If seqfans add any other bijective mappings that are in OEIS, then at some
point these can be copied to the other sequences.

Best Regards,
Peter

On Mon, March 2, 2020 8:08 pm, Peter Munn wrote:
> On Mon, March 2, 2020 4:58 pm, Peter Luschny wrote:
>> NS> For me, without doubt, the best map is the classic map based NS> on
the Stern's diatomic series (or Stern-Brocot sequence, A002487. For me
it is the Euclid tree: A295515.
> I cast my vote for the Sagher map, A071974(n)/A071975(n), which is
nicely
> multiplicative.
> Best Regards,
>  Peter
>> NS> from 1858: Look at all the references there.
>> Let's wait and see. In 160 years, we can count references again. If you
have Maple you can also try this delightful implementation:
>>     magic := x -> 1/(1 + floor(x) - frac(x)):
>> And then run:
>>     0; do magic(%) od;
>> Cheers, Peter
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>> Seqfan Mailing list - http://list.seqfan.eu/
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