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

1,2

Comments

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

Links

Table of n, a(n) for n=1..15.

Example

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

Prog

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

Crossrefs

Cf. A001597, A005117, A216765, A280005.

Sequence in context: A009584 A013562 A081681 * A141774 A141349 A018427

Adjacent sequences: A281937 A281938 A281939 * A281941 A281942 A281943

Keyword

nonn,more

Author

Altug Alkan, Feb 24 2017

Extensions

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

Status

approved