Q: OEIS duplicates?

[Maximilian Hasler]

On Tue, Apr 29, 2008 at 1:38 PM, Richard Mathar
<mathar at strw.leidenuniv.nl> wrote:
>  Are these OEIS duplicates:
>  A138980 and A049561 (apart from the first value)?

NO, cf.

>  A138917 and A061242 ?

A061242  	 	 Prime numbers == 8 (mod 9)
A138917 		Primes of the form 18n-1.

YES:
we have :
x=9n-1 <=> x = 18n-1 or x=18n+8
However, there is no prime of the latter form.

Maximilian