A124272 Primes in A124271, or primes of the form Sum_{i=1..k} (prime(i)^k - 1)/(prime(i) - 1).

7, 1469991559, 2994181661163361882651

Offset: 1

Author

Alexander Adamchuk, Oct 23 2006

Keywords

• nonn
• bref
• hard

Comments

The corresponding values of k are 2, 8, 14, ...

The next value of k is 667, so a(4) = 7.753...*10^2462. - Amiram Eldar, Jul 13 2025

Examples

			7 is a term because A124271(2) = 7 is prime.
		

Crossrefs

Cf. A124271.

Programs

Mathematica

Do[f=Sum[(Prime[i]^n-1)/(Prime[i]-1),{i,1,n}];If[PrimeQ[f],Print[{n,f}]],{n,1,100}]