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Numbers n such that 1 + Sum k^k (k=1..n) is prime.
3

%I #2 Mar 31 2012 13:20:28

%S 1,52,124,431

%N Numbers n such that 1 + Sum k^k (k=1..n) is prime.

%C Primes of the form A001923[n] = Sum k^k (k=1..n) are given in A073826[n] and their indices are given in A073825[n] = {2,5,6,10,30,...}.

%t s=1; Do[s=s+k^k;If[PrimeQ[s],Print[{k,s}]],{k,1,500}]

%Y Cf. A073825, A001923.

%K nonn

%O 1,2

%A _Alexander Adamchuk_, Aug 23 2006