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A235425 Numbers n such that between n and the next prime there are gpf(n) numbers, where gpf(n) denotes the largest prime factor of n. 3
8, 64, 128, 625, 729, 1701, 2625, 3025, 4096, 6435, 8505, 10115, 12675, 14641, 17303, 19343, 19683, 19845, 21125, 25515, 25725, 26325, 26741, 27783, 32768, 33075, 33275, 34075, 35721, 38025, 39375, 42525, 43875, 50193, 59319, 60835, 61731, 70805, 75411, 75803 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..10000

EXAMPLE

64 = 2^6, whose largest prime factor is 2, is in the sequence because between 64 and 67 (the next prime) there are 2 numbers, 65 and 66.

MATHEMATICA

Select[Range[10^5], NextPrime[#] - # == 1 + FactorInteger[#][[-1, 1]] &]

PROG

(PARI) gpf(n)=n=factor(n)[, 1]; n[#n]

is(n)=nextprime(n)-n==gpf(n)+1 \\ Charles R Greathouse IV, Jan 10 2014

CROSSREFS

Cf. A050765, A105779.

Sequence in context: A116978 A125110 A209990 * A255932 A043152 A044195

Adjacent sequences:  A235422 A235423 A235424 * A235426 A235427 A235428

KEYWORD

nonn

AUTHOR

Giovanni Resta, Jan 10 2014

STATUS

approved

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Last modified August 10 11:12 EDT 2020. Contains 336379 sequences. (Running on oeis4.)