[seqfan] Re: Fun and quick permutation (with a digital root)

[M. F. Hasler]

Dear Eric,
I confirm your values modulo the typo "17"(wrong?) instead of "14"(my
PARI suggests) near the end of your list.
Proposed as https://oeis.org/draft/A248025
M.

On Mon, Sep 29, 2014 at 11:05 AM, Eric Angelini <Eric.Angelini at kntv.be> wrote:
>
> Hello SeqFans (last posting of the day, my apologizes)
>
> Here is another simple permutation of the integers > 0.
> Start S with a(1) = 1
> Extend S with the smallest unused integer so far such
> that a(n+1) starts with the digital root of a(n). I get:
>
> S = 1,10,11,2,20,21,3,30,31,4,40,41,5,50,51,6,60,61,7,70,71,8,80,81,9,90,91,12,32,52,72,92,22,42,62,82,13,43,73,17,53,83,23,...
>
> Example:
> 10 is the smallest available integer with '1' as leftmost digit
>    -- this '1' being the digital root of a(1);
> 11 is the smallest available integer with '1' as leftmost digit
>    -- this '1' being the digital root of a(2);
>  2 is the smallest available integer with '2' as leftmost digit
>    -- this '2' being the digital root of a(3);
> 20 is the smallest available integer with '2' as leftmost digit
>    -- this '2' being the digital root of a(4);
> ...
> [look now at the present end of S]:
> ...
> 23 is the smallest available integer with '2' as leftmost digit
>    -- this '2' being the digital root of the term coming before 23
>    (the digital root of 83 is 8+3=11 then 1+1=2)
>
> Best,
> É.
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-- 
Maximilian