[seqfan] Re: Sets of composite numbers

Neil Sloane njasloane at gmail.com
Tue Jul 29 12:40:04 CEST 2014


I've changed the definition of A189118 as suggested by Don Reble,
while A075067 seems OK.

If anyone would like to add the other version(s) that have been
discussed here, please do so!
Neil


On Tue, Jul 29, 2014 at 1:42 AM, Don Reble <djr at nk.ca> wrote:

> First, note that these are different: A075067 claims to be looking for
>> at least n consecutive, while A189118 is looking for exactly n.
>>
>
>    Other way 'round, actually.
>
>    I say A075067 is correct. It is a trivial variation of A000230 and
>    A045881; perhaps it should refer to them.
>
>
>  In A075067, a(4) through a(6) should all be 115. There are probably
>> further errors.
>>
>
>    In A189118, that is. The stated definition gives A100964(n+1)+2.
>    But the A189118 terms are
>        a(n) = smallest composite (odd) number greater than a(n-1),
>        such that a(n)+2n is the first prime after a(n).
>    I guess that's what the Mathematica program produces. (Can someone
>    confirm that?)
>
> --
> Don Reble  djr at nk.ca
>
>
>
> _______________________________________________
>
> Seqfan Mailing list - http://list.seqfan.eu/
>



-- 
Dear Friends, I have now retired from AT&T. New coordinates:

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



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