# RE : Self describing it's primes

Eric Angelini Eric.Angelini at kntv.be
Tue Mar 18 02:27:44 CET 2008

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Oooops, yes, I understand now -- sorry!
See my previous post for the rule I had in mind!
(and forget those seq -- as I've been told privately
they are of no interest -- and I kind of agree!)
Best,
E.

________________________________

De: Gabriel Cunningham [mailto:gabriel.cunningham at gmail.com]
Date: mar. 18/03/2008 02:20
À: Marc LeBrun
Cc: seqfan at ext.jussieu.fr
Objet : Re: Self describing it's primes

It seems that as given, the sequence is actually:

a(n) is always the smallest unused non-prime, except when a(n) must be a prime; if so, a(n) is the smallest unused prime greater than a(n-1).

If we drop that last restriction, I get the first few terms to be:
1, 2, 4, 3, 6, 8, 5, 9, 10, 12, 7, 14, 15, 11, 16, 18, 13, 17, 19, 20, 21, 23, 22, 24, 29

Gabe

On Mon, Mar 17, 2008 at 9:15 PM, Marc LeBrun <mlb at well.com <mailto:mlb at well.com> > wrote:

3?  7?
Needs
work?

At 05:44 PM 3/17/2008, Eric Angelini wrote:

Hello SeqFans,

1,2,4,5,6,8,11,12,13,14,17,18,20,23,24,25,26,29,...

"Move a(n) steps to the right and you will bump into a prime"

a(n) is always the smallest unused non-prime, except when a(n) must be a prime; if so, a(n) is the smallest unused prime.

Could someone check this seq, calculate some more terms and submit them to the OEIS, if of interest?

Best,
E.

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