[seqfan] Re: Strict divisors and digits of a(n)

[Eric Angelini]

Many thanks to Olivier and Gérard!
Best 
É.

> Le 1 déc. 2013 à 21:39, "Charles Greathouse" <charles.greathouse at case.edu> a écrit :
> 
> The English term is "proper divisor". This sequence appears as A132080.
> 
> Charles Greathouse
> Analyst/Programmer
> Case Western Reserve University
> 
> 
>> On Sun, Dec 1, 2013 at 3:20 PM, Eric Angelini <Eric.Angelini at kntv.be> wrote:
>> 
>> 
>> Hello SeqFans,
>> I don't know if "strict divisor" (SD) is
>> the English translation of the French
>> "strict diviseur" -- anyway you will
>> understand if I say that the SDs of
>> 6 are 1,2 and 3, and (second example),
>> the SDs of 28 are 1,2,4,7 and 14.
>> 
>> Now consider S:
>> a(n) will _not_ be part of S if one digit
>> of a(n) can be found in one of its SDs:
>> 
>> S=2,3,4,5,6,7,8,9,23,27,29,34,38,...
>> 
>> SDs of the above integers (2nd column):
>> 2=1
>> 3=1
>> 4=1,2
>> 5=1
>> 6=1,2,3
>> 7=1
>> 8=1,2,4
>> 9=1,3
>> 23=1
>> 27=1,3,9
>> 29=1
>> 34=1,2,17
>> 38=1,2,19
>> ...
>> We see that for the above integers,
>> no digit at the left of the equal sign
>> is repeated at the right of the sign.
>> 
>> My (naive?) question is:
>> -- Is S finite?
>> 
>> Best,
>> É.
>> 
>> 
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