Corrected On sequence nXn where x equal 09,18,27,36,45,54,63,72,81,90

[f.firoozbakht at sci.ui.ac.ir]

> Can anyone find n such that n09n,
> n18n,n27n,n36n,n45n,n54n,n63n,n72n,n81n,n90n, are all primes
> 
> where n09n designe concatenation of (n 09 n) (example 1091 is prime,
> 310931 is prime)


If we define a(m) as the smallest number n such that 
all the m numbers : 

          n.09.n, n.2*9.n, ...,n.(m-1)*9.n & n.m*9.n

are primes, in fact you want a(10).

The first six terms of this sequence are : 

                              1,47,251,9269,15533,1763897

example: 1763897 is the smallest number n such that all six numbers 
n.09.n, n.18.n, ...,n.54.n are primes.
(1763897091763897,1763897181763897,1763897271763897,1763897361763897,
1763897451763897 & 1763897541763897  are primes.)

I think we can find at most two more terms of this sequence and a(10)
is too large ,so we can not find it.

Regards

Farideh

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