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%I #3 Mar 31 2012 10:22:01
%S 2,5,11,23,47,971,191,383,22136835839,1310719,2259801991,6143,
%T 353563778431304822783,91424858111,5425784582791,57395627,21474836479,
%U 1099999999999999999,786431,13508517176729920889
%N Smallest prime of the form k^n + k^(n-1) - 1.
%C Primes arising in A125973.
%e Consider n = 10. k^n + k^(n-1) - 1 evaluates to 1, 1535, 78731, 1310719 for k = 1, ..., 4. Only the last of these numbers, 4^10+4^9-1 = 1310719, is prime, hence a(10) = 1310719.
%o (PARI) {for(n=1,20,k=1;while(!isprime(a=k^n+k^(n-1)-1),k++);print1(a,","))} - Klaus Brockhaus, Dec 17 2006
%Y Cf. A000040, A045546, A125881-A125885, A125965-A125973.
%K nonn
%O 1,1
%A _Artur Jasinski_, Dec 14 2006
%E Edited and extended by _Klaus Brockhaus_, Dec 17 2006
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