A281940 Least k such that k^n + 1 is the product of n distinct primes (k > 0).

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

Offset: 1

Author

Altug Alkan, Feb 24 2017

Keywords

• nonn
• more

Comments

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

Examples

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

Crossrefs

Cf. A001597, A005117, A216765, A280005.

Programs

PARI

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

Extensions

a(14)-a(15) from Giovanni Resta, Mar 10 2017