Extract of a letter from the father Mr. Euler to Mr. Bernoulli, concerning the Mémoire published among those of 1771
This is a very short note about properties of the numbers 10p, along with criteria for them to be divisible by 2p+1. It also contains a remark that 231–1 is prime and that 41–x+xx produces prime numbers for every integer value of x from 0 to 40.
Original Source Citation
Nouveaux Mémoires de l'académie royale des sciences de Berlin, Volume 1772, pp. 35-36.
Opera Omnia Citation
Series 1, Volume 3, pp.335-337.