

A033849


Numbers n whose prime factors are 3 and 5.


20



15, 45, 75, 135, 225, 375, 405, 675, 1125, 1215, 1875, 2025, 3375, 3645, 5625, 6075, 9375, 10125, 10935, 16875, 18225, 28125, 30375, 32805, 46875, 50625, 54675, 84375, 91125, 98415, 140625, 151875, 164025, 234375, 253125, 273375, 295245
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OFFSET

1,1


COMMENTS

n such that phi(n)=(8/15)*n.  Benoit Cloitre, Apr 19 2002
A143201(a(n))=3; subsequence of A143202; a(n)=15*A003593(n).  Reinhard Zumkeller, Sep 13 2011


LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000


MATHEMATICA

Sort[Flatten[Table[Table[3^j*5^k, {j, 1, 10}], {k, 1, 10}]]] (* Geoffrey Critzer, Dec 07 2014 *)


PROG

(Haskell)
import Data.Set (singleton, deleteFindMin, insert)
a033849 n = a033849_list !! (n1)
a033849_list = f (singleton (3*5)) where
f s = m : f (insert (3*m) $ insert (5*m) s') where
(m, s') = deleteFindMin s
 Reinhard Zumkeller, Sep 13 2011


CROSSREFS

Cf. A033845, A033846, A033847, A033848, A033850, A033851.
Subsequence of A256617.
Sequence in context: A298462 A066763 A164788 * A194715 A060536 A014634
Adjacent sequences: A033846 A033847 A033848 * A033850 A033851 A033852


KEYWORD

nonn


AUTHOR

Jeff Burch


EXTENSIONS

Offset and typo in data fixed by Reinhard Zumkeller, Sep 13 2011


STATUS

approved



