[seqfan] Re: Typo in B-file for A063539

[Fred Lunnon]

<< I wonder how typos like this can creep in -- the text of the B-file ought
to be copied directly from program output, and never pass through human
editorial hands which might drop a digit, as seems to have happened here. >>

  One hazard is that standard output from one application (eg. CAS) is
rarely completely compatible with standard input to another (eg. OEIS):
as a result, trivial intermediate editing will be required to convert the data.
Instead of developing (and testing!) some special-purpose script for an
expected one-time run, it usually appears more attractive just to fix
things up manually.

  What could possible go wrong ... ?!

WFL



On 4/2/20, Neil Sloane <njasloane at gmail.com> wrote:
> Allan, you said
>> A(7910) ought to be 29925 (the example I gave above), but is instead
>> given
> as 9925,
>
> Actually the b-file says A(7910) = 9795, and A(7943) = 9925.  I think that
> illustrates how errors creep in!!
>
>
> I am recomputing the b-file.
>
> Thanks for the heads-up
>
> Best regards
> Neil
>
> 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.
> Phone: 732 828 6098; home page: http://NeilSloane.com
> Email: njasloane at gmail.com
>
>
>
> On Thu, Apr 2, 2020 at 12:37 PM Allan Wechsler <acwacw at gmail.com> wrote:
>
>> A063539 collects numbers whose largest prime factor is less than the
>> square
>> root. For example, 29925 = 3^2 * 5^2 * 7 * 19, and 19^2 is only 361, much
>> smaller than 29925.
>>
>> An interesting feature of this sequence is that it has constant
>> asymptotic
>> density; HAKMEM item 29 (Schroeppel) identifies the density as (1 - ln
>> 2),
>> without proof.
>>
>> Because of this intriguing feature, it's interesting to look at the graph
>> (which of course looks like a straight line), and this reveals an odd
>> blot
>> under the line, which I have traced to a typo in the B-file.
>>
>> A(7910) ought to be 29925 (the example I gave above), but is instead
>> given
>> as 9925, which should not be in the sequence because its largest prime
>> factor is 397.
>>
>> I wonder how typos like this can creep in -- the text of the B-file ought
>> to be copied directly from program output, and never pass through human
>> editorial hands which might drop a digit, as seems to have happened here.
>>
>> (Also, the comments should include the slope of the line, ideally with a
>> citation to someplace that proves the identity.)
>>
>> --
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>>
>
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