[seqfan] Re: Wrong formula in A091050
njasloane at gmail.com
Wed Apr 29 03:09:47 CEST 2020
I agree with Robert Israel
Neil J. A. Sloane, President, OEIS Foundation.
11 South Adelaide Avenue, Highland Park, NJ 08904, USA.
Also Visiting Scientist, Math. Dept., Rutgers University, Piscataway, NJ.
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Email: njasloane at gmail.com
On Tue, Apr 28, 2020 at 1:32 PM <israel at math.ubc.ca> wrote:
> The author of that formula seems to have forgotten that there could be
> perfect powers divisible by more than one prime. I think any "repair"
> have very little resemblance to the current formula. My suggestion would
> to delete.
> On Apr 28 2020, Ami Eldar wrote:
> >Dear SeqFans,
> >The first formula in A091050 (Number of divisors of n that are perfect
> >powers.) is wrong:
> >a(n) = A073093(n)-A001221(n) = A001222(n)-A001221(n)+1.
> >(the 2nd equals sign is correct).
> >This formula is wrong for the values of n = 36, 72, 100, 108, 144, 180,...
> >E.g. 36 has 4 divisors that are perfect powers 1, 4, 9, 36,
> >yet A001222(36)-A001221(36)+1 = 4 - 2 + 1 = 3.
> >My question is whether this formula is repairable, or should it be
> >Seqfan Mailing list - http://list.seqfan.eu/
> Seqfan Mailing list - http://list.seqfan.eu/
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