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Least k such that k^n + 1 is the product of n distinct primes (k > 0).
3

%I #21 Mar 12 2017 06:10:41

%S 1,3,9,43,46,47,245,1697,109,565,3938,3255,30089,18951,2217

%N Least k such that k^n + 1 is the product of n distinct primes (k > 0).

%C Corresponding values of k^n + 1 are 2, 10, 730, 3418802, 205962977, 10779215330, ...

%e a(3) = 9 because 9^3 + 1 = 2 * 5 * 73 and 9 is the least number with this property.

%o (PARI) a(n) = my(k=1); while (!issquarefree(k^n+1) || omega(k^n+1) != n, k++); k;

%Y Cf. A001597, A005117, A216765, A280005.

%K nonn,more

%O 1,2

%A _Altug Alkan_, Feb 24 2017

%E a(14)-a(15) from _Giovanni Resta_, Mar 10 2017