(Petropoli (St. Petersbourg), 1750). 4to. Uncut, without wrappers. Extracted from ""Novi Commentarii Academiae Scientiarum Imperialis Petropolitanae"", Tom. I. ad Annum 1747 et 1748. Pp. 3-19 a. 1 engraved plate., and pp. 20-48.
First printing of both papers. The second is important as it contains Euler'is second proof of the Euler-Fermat theorem, which Euler presents as a consequence of the theorem that (a+b)p = ap+bp (mod p). This paper also includes results about possible divisors of a2n + b2n, and Euler uses this to show again that F5 is not prime. - Enestroem No. 133 a. 134.