# [seqfan] Re: Digitsum and length

Neil Sloane njasloane at gmail.com
Wed Feb 19 17:06:14 CET 2020

```Nice sequence, Eric!  Hope you will submit it (if you didn't already)!

Best regards
Neil

Neil J. A. Sloane, President, OEIS Foundation.
11 South Adelaide Avenue, Highland Park, NJ 08904, USA.
Also Visiting Scientist, Math. Dept., Rutgers University, Piscataway, NJ.
Email: njasloane at gmail.com

On Wed, Feb 19, 2020 at 7:22 AM Lars Blomberg <larsl.blomberg at comhem.se>
wrote:

> Hello!
>
> The sequence continues
> 1, 2, 10, 3, 100, 4, 1000, 5, 10000, 6, 100000, 7, 1000000, 8, 10000000,
> 9, 100000001, 11, 12, 101, 13, 1001, 14, 10001, 15, 100001, 16, 1000001,
> 17, 10000001, 18, 100000002, 102, 103, 1002, 104, 10002, 105, 100002, 106,
> 1000002, 107, 10000002, 108, 100000003, ...
>
> Among the first 10000 terms the largest value is
> 10000000000000000000000003.
> For 100000 terms it is 1000000000000000000000000000000004.
> Computing 100000001 terms is unfortunately out of the reach of my computer.
>
> /Lars B
>
> -----Ursprungligt meddelande-----
> Från: SeqFan <seqfan-bounces at list.seqfan.eu> För Éric Angelini
> Skickat: den 18 februari 2020 12:08
> Till: Sequence Discussion list <seqfan at list.seqfan.eu>
> Ämne: [seqfan] Digitsum and length
>
>
> Hello SeqFans,
> say that "The digitsum of a(n) is the
> length of a(n+1)" -- we then get (with S being the lexicographically
> earliest seq of such distinct integers):
> S = 1,2,10,3,100,4,1000,5,10000,6,100000,
> 7,1000000,8,10000000,9,100000001,
> 11,12,101,12,1001,...
> We see above after 9 that the next
> integer cannot be 100000000 (length  9)
> because this integer has digitsum 1 and
> all integers with digitsum 1 have been
> used already in S; thus 100000001
> after 9 (with digitsum 2), followed by
> 11 (length 2), as 10 (same length) is
> S is infinite, of course, but in computing its terms one must be careful
> because of this "limited available lengths" story.
> Any takers (if interested)? -- I'd love to see a 100000001-term graph (!)
> Best, É.
>
>
>
>
>
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>
>
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>

```