# [seqfan] Re: Non primes and non prime remainders

Sun Oct 5 14:45:47 CEST 2014

```Beginning with the second term, if a(n)+1 is prime, then a(n+1)=a(n)+4,
otherwise, a(n+1)=a(n)+1.

Regards,
________________________________________
From: SeqFan [seqfan-bounces at list.seqfan.eu] on behalf of Eric Angelini [Eric.Angelini at kntv.be]
Sent: 05 October 2014 12:34
To: Sequence Discussion list
Subject: [seqfan] Non primes and non prime remainders

Hello SeqFans,
C is the "sister" sequence of the previous one.
C starts with c(1)=1 and is always extended
with the smallest non prime c(n) such that
c(n)/c(n-1) has a non prime remainder.
We get (if I'm not wrong):

C=1,4,8,9,10,14,15,16,20,21,22,26,27,28,32,33,34,35,36,40,...

Best,
É.

[if of interest, the "panaché" sequences could be computed and added
to the OEIS too:

C' starts with 1 and C' is extended with the
smallest non prime c'(n) such that c'(n)/c'(n-1)
has a prime remainder;

P' starts with 2 and P' is extended with the
smallest prime p'(n) such that p'(n)/p'(n-1)
has a non prime remainder.]

Best,
É.
Catapulté de mon aPhone

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