A108405 Numbers n such that a^u + b^u + c^u + ... is prime, where a*b*c* ... is the prime factorization of n and u is the largest prime dividing n.

12, 28, 40, 48, 54, 80, 90, 96, 104, 108, 224, 350, 384, 390, 432, 500, 567, 570, 660, 686, 720, 770, 775, 810, 972, 1085, 1176, 1551, 1575, 1875, 2016, 2400, 2560, 2600, 2700, 2760, 2829, 2880, 2925, 3072, 3456, 3640, 3645, 3888, 4260, 4374, 4400, 4692

Offset

1,1

Links

Table of n, a(n) for n=1..48.

Example

a(2)=28 because 28=2*2*7 and 2^7 + 2^7 + 7^7 = 823799, a prime.

Crossrefs

Cf. A006530.

Sequence in context: A141274 A224613 A134618 * A184838 A044073 A044454

Adjacent sequences: A108402 A108403 A108404 * A108406 A108407 A108408

Keyword

nonn

Author

Jason Earls, Jul 04 2005

Extensions

More terms from Ryan Propper, Feb 11 2008

Status

approved