## Primes Obtained Concatenating to the Left a Prime Having an Odd Prime Digit Sum S with a Divisor of S-1

**Authors:** Marius Coman

In a previous paper, “Primes obtained concatenating a Poulet number P with (s - 1)/n where s digits sum of P and n is 2, 3 or 6”, I noticed that in almost all the cases that I considered if a prime was obtained through this concatenation than the digits sum of P was a prime. That gave me the idea for this paper where I observe that for many primes p having an odd prime digit sum s there exist a prime obtained concatenating p to the left with a divisor of s – 1 (including 1 and s – 1).

**Comments:** 2 Pages.

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### Submission history

[v1] 2017-05-07 08:51:48

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