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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. 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
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
KEYWORD
nonn
AUTHOR
Jason Earls, Jul 04 2005
EXTENSIONS
More terms from Ryan Propper, Feb 11 2008
STATUS
approved

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Last modified June 17 10:05 EDT 2024. Contains 373445 sequences. (Running on oeis4.)