[seqfan] Re: Divisors of the concatenation of n+1 and n

[Eric Angelini]

Merci beaucoup, Reinhard !
:-D
Regards,
É.
Catapulté de mon aPhone

> Le 3 juin 2015 à 15:29, Reinhard Zumkeller <reinhard.zumkeller at gmail.com> a écrit :
> 
> https://oeis.org/draft/A256285
> Best
> R.
> 
> 
> 2015-06-03 11:48 GMT+02:00 Eric Angelini <Eric.Angelini at kntv.be>:
> 
>> Hello SeqFans,
>> t(n) is the smallest unused integer so far in T such that t(n) is a
>> divisor of the concatenation of n+1 and n.
>> 
>>     n =  1  2  3  4  5  6  7  8  9   10   11   12   13   14   15   16
>> 17   18   19   20   21   22
>> concat = 21 32 43 54 65 76 87 98 109 1110 1211 1312 1413 1514 1615 1716
>> 1817 1918 2019 2120 2221 2322
>>     T =  1, 2 43, 3, 5, 4,29, 7,109,  6,  173,  8,   9,  757, 17,  11,
>> 23,  14,  673, 10, 2221, 18,...
>> 
>> Example:
>> The divisors of 1413 (concatenation of 14 and 13) are 1, 3, 9, 157, 471
>> and 1413. As 1 and 3 appear already in T, we have t(13) = 9.
>> 
>> Is T a permutation of the integers > 0 ?
>> 
>> Best,
>> É.
>> 
>> 
>> 
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>> 
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> 
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