[seqfan] Re: A245486

[Jack Brennen]

Actually, it's impossible.  2^n+1 is never divisible by 23, and
when 2^n-1 is divisible by 23, it's also divisible by 89.

So 46 cannot occur in the sequence.



On 7/23/2014 3:25 PM, Jack Brennen wrote:
> When do you get the number 46 in the sequence?
>
> That would imply 2^n-1 or 2^n+1 with largest prime factor 23, which
> seems unlikely.
>
>
>
>
> On 7/23/2014 2:59 PM, Frank Adams-Watters wrote:
>> I have a new sequence in editing state: https://oeis.org/draft/A245486 -
>> Greatest prime factor of n times greatest prime factor of n+1.
>>
>> 1) I think it's the case that recent results show that this sequence
>> goes to infinity; equivalently, each member of A006881(products of 2
>> distinct primes) occurs only finitely many times. Can someone confirm
>> this?
>>
>> 2) I can almost prove that every member of A006881 does occur in this
>> sequence. Can anyone find a proof? (Or a counterexample.)
>>
>> Franklin T. Adams-Watters
>>
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>