[seqfan] Re: help wanted: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 101, 21, ...
Michael Branicky
branicky at gmail.com
Wed Feb 22 22:48:52 CET 2023
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Marc, for a different take on this, see A276769 <https://oeis.org/A276769>
Regards,
Michael
On Wed, Feb 22, 2023 at 3:40 PM Marc LeBrun <mlb at well.com> wrote:
> [apologies if this is a duplicate]
>
> To my surprise, I find 10,20,30,40,50,60,70,80,90,100,101,21,... is NOT in
> the OEIS.
>
> The definition I had in mind was "Next larger integer with the same
> decimal digits as n."
>
> It is the decimal analog of the base-2 version A057168, "Next larger
> integer with same binary weight (number of 1 bits) as n."
>
>
> I'd love to see it in the OEIS, but I don't have time to code up a
> generator, much less submit a properly complete entry for it.
>
> >> Would someone here be willing to take this on?
>
>
> It should cross-reference the similar -- but critically different in
> spirit -- sequence A354049, "The smallest number that includes all the
> digits of n but does not equal n."
>
>
> Note that A057168 can be computed using Bill Gosper's elegant algorithm
> from HAKMEM Item #175.
>
> If there's a decimal version of that code that somehow uses some kind of
> Lunar arithmetic operations or something, I'd surely love to see it!
>
>
> Of course the numbers that are NOT in A057168 are simply A000225, "a(n) =
> 2^n - 1."
>
> Similarly, the integers that are NOT in this proposed sequence are
> A009994, "Numbers with digits in nondecreasing order." (So, some more
> cross-refs needed...)
>
>
> Then there is the sibling permutation, "Numbers whose digits are not
> monotonically increasing."
>
> And from that the sequences giving the actual permutations... And so
> on...
>
>
> Apologies for just sketching this and running away, but alas due to
> personal limitations I really can't make OEIS-worthy submissions right now,
> so many thanks to anyone who takes this further.
>
>
> --
> Seqfan Mailing list - http://list.seqfan.eu/
>
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