[seqfan] Re: A090709 Decimal primes whose decimal representation in base 6 is also prime.

[Veikko Pohjola]

Originally the naming of a sequence built from the converted forms of decimal primes "Decimal primes whose decimal representation in base b is also prime" appears in all those published with b = 2, 3, 4, 5, 6 or 7, that is A089971, A089981, A090707, A090708, A090709 and A090710 (all by the same author) and with b = hex in A103144 (by another author).  

Now A090707, A090708, A090709 have been renamed for b = 4, 5 and 6 as ”Primes whose decimal representation is a valid number in base b and interpreted as such is again a prime” 

A090710 has been renamed ”Primes with digits less that 7 whose decimal representation is also a prime when interpreted in base 7”.

A089971, A089981 appear still under the original title for b = 2 and 3. I propose that these will be renamed appropriately.
(A089981 is crossreferenced in A089974. Why?)

A103144 is not a sequence built from the converted forms of decimal primes but a sequence of the decimal primes themselves subjected to the conversion. Thus its naming seems acceptable, but there are now various namings for the same purpose:
"Decimal primes whose decimal representation in hex is also prime"
”Primes which when written in base 4 then interpreted in base again give primes” (A065722)
”Primes whose base-10 representation also represents a prime in base b” with b=13 and 17 (A235110, A235126)
Should there be some unification of the terminology?
Regards, Veikko


Charles Greathouse kirjoitti 3.1.2014 kello 17.20:

> I agree that the name is lacking. I suggest
> 
> Primes p such that the base-6 representation of p, read in decimal, is also
> prime.
> 
> or
> 
> Primes with a base-6 representation which, read in decimal, is also prime.
> 
> but you may have better ideas.
> 
> Charles Greathouse
> Analyst/Programmer
> Case Western Reserve University
> 
> 
> On Fri, Jan 3, 2014 at 4:10 AM, Veikko Pohjola <veikko at nordem.fi> wrote:
> 
>> Dear seqfans,
>> 
>> A090709 lists the numbers which are obtained by converting first all
>> (decimal) primes into base 6 and then keeping those whose digits make a
>> decimal prime. The title of the sequence is "Decimal primes whose decimal
>> representation in base 6 is also prime". Maybe I misunderstand what the
>> title says, but I would expect the sequence to be composed of those decimal
>> primes, which after conversion yield the appropriate digits, but not the
>> primes which the digits make.
>> 
>> The example given by the author tells that  "19 is prime in decimal and 19
>> base 6 is 31, which is also prime in decimal". I would thus expect 19 to be
>> the prime that the title refers to rather than 31. Hereby the title, as it
>> is written, would actually refer to A065724 titled "Primes p such that the
>> decimal representation of its base 6 conversion is also prime". The example
>> given for  A065724 is formally identical with the example above: "19(10) =
>> 31(6) is prime but also 31(10)".
>> 
>> Should the title of A090709 be deciphered or is it only my insufficient
>> English which is the problem here?
>> Veikko
>> 
>> 
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