[seqfan] Re: A058054

Max Alekseyev maxale at gmail.com
Thu Jul 24 03:16:55 CEST 2014


I suggest to remove A058054(1) as undefined and start with offset 2.

Regards,
Max


On Wed, Jul 23, 2014 at 8:41 PM, Hans Havermann <gladhobo at teksavvy.com> wrote:
> https://oeis.org/A058054
> nextprime(n!)-prevprime(n!).
>
> "For n!=1,2,6,24,120 nextprime(n!)=2,3,7,29,127 while prevprime(n!)=-2,2,5,23,113 so their difference is: a(n)=4,0,2,6,14,.."
> Formula: a(n) = A037151(n) - A006990(n)]
>
> The name and formula are at odds over the first two terms. To get a(1) we cannot use the formula because A006990(1) is undefined. So the author uses the name and suggests prevprime(1!) = -2. But then for a(2) he ignores the name, because prevprime(2!) = -2 as well, not 2, (yielding a difference of 5), and relies instead on the formula. But doesn't subtract correctly!
>
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