[seqfan] Re: New on wiki: Help Page, Eponymous index, Index to Fractions

[Kevin Ryde]

njasloane at gmail.com (Neil Sloane) writes:
>
> 3400 sequences with keyword "frac".

A possibility without frac could be the Stern diatomic A002487 where
a(n)/a(n+1) is all positive rationals.  That's the Calkin-Wilf tree by
rows and n bit-reversed (A059893) of Stern-Brocot A007305/A007306 now in
the list.

A191379 by Song Heng Chan generalizes to enumerate as a(n)/a(n+1) too.
It's num,den not both odd, and possibly a common factor 3^m to divide
out.




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