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A033851
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Numbers n whose prime factors are 5 and 7.
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9
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35, 175, 245, 875, 1225, 1715, 4375, 6125, 8575, 12005, 21875, 30625, 42875, 60025, 84035, 109375, 153125, 214375, 300125, 420175, 546875, 588245, 765625, 1071875, 1500625, 2100875, 2734375, 2941225, 3828125, 4117715, 5359375, 7503125
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Contribution from Artur Jasinski (grafix(AT)csl.pl), Nov 09 2008: (Start)
Successive k such that EulerPhi[k]/k == 24/35.
a(n)=35*A003595(n) (End)
A143201(a(n)) = 3; subsequence of A143202. [Reinhard Zumkeller, Sep 13 2011]
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LINKS
| Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
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MATHEMATICA
| a = {}; Do[If[EulerPhi[x]/x == 24/35, AppendTo[a, x]], {x, 1, 10000}]; a [From Artur Jasinski (grafix(AT)csl.pl), Nov 09 2008]
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PROG
| (Haskell)
import Data.Set (singleton, deleteFindMin, insert)
a033851 n = a033851_list !! (n-1)
a033851_list = f (singleton (5*7)) where
f s = m : f (insert (5*m) $ insert (7*m) s') where
(m, s') = deleteFindMin s
-- Reinhard Zumkeller, Sep 13 2011
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CROSSREFS
| A003595, A147571-A147575, A147576-A147580 [From Artur Jasinski (grafix(AT)csl.pl), Nov 09 2008]
Cf. A033845, A033846, A033847, A033848, A033849, A033850.
Sequence in context: A154074 A015219 A195545 * A194716 A101954 A005937
Adjacent sequences: A033848 A033849 A033850 * A033852 A033853 A033854
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KEYWORD
| nonn
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AUTHOR
| Jeff Burch (gburch(AT)erols.com)
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EXTENSIONS
| Offset fixed by Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Sep 13 2011
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