[seqfan] Re: sum of prime factors of p-1 and p+1

[Charles Greathouse]

I'm extending A086711 to 4e9 at the moment, from which it is easy to derive
terms of the sequence using sopfr.  I suppose this means we should add three
sequences: the sopf analogue of A086711 and the sopf(r)-must-be-prime
variants.  Anyone up to the task?

Charles Greathouse
Analyst/Programmer
Case Western Reserve University


On Mon, May 16, 2011 at 5:38 PM, N. J. A. Sloane <njas at research.att.com>wrote:

> But A086711 doesn't require that the sum of prime factors of p-1 and p+1
> be a prime - although it IS in all the terms shown!
> Is it always? If so, why? If not, there should be another sequence
> (or two) with the other version and the exceptions.
>
> Neil
>
>
>
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