# [seqfan] Re: Is this right? smallest prime factor of smaller of amicable pair

Jonathan Post jvospost3 at gmail.com
Mon Aug 16 17:43:10 CEST 2010

```Thank you both, Tony and Charles!  I always like it when a sequence
that seems stuck in the mud digs its tires out, and climbs onto higher
ground.

So there should be a comment akin to:
"The first value other than 2 or 3 was found by Charles Greathouse as
a(?) = 5480828320492525 = 5^2 * 7^2 * 11 * 13 * 17 * 19 * 23 * 31 * 103 * 1319

On Sun, Aug 15, 2010 at 11:48 PM, Charles Greathouse
<charles.greathouse at case.edu> wrote:
> It doesn't hold: 5480828320492525.
>
> Charles Greathouse
> Analyst/Programmer
> Case Western Reserve University
>
> On Mon, Aug 16, 2010 at 2:24 AM, T. D. Noe <noe at sspectra.com> wrote:
>> At 11:14 PM -0700 8/15/10, Jonathan Post wrote:
>>>2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 3, 3, 2, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2,
>>>2, 2, 2, 2, 2, 2, 3, 2, 2
>>>smallest prime factor of smaller of amicable pair
>>>a(n) = A020639(A002025(n)) =   Lpf(A002025(n)) = sigma(A002025(n))-A002025(n).
>>>Must always be 2 or 3?
>>
>>
>> It is true for all the terms in the b-file for A063990, which includes the
>> larger of the amicable pair also.
>>
>> Tony
>>
>>
>>
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```