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 A033851 Numbers n whose prime factors are 5 and 7. 13
 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; text; internal format)
 OFFSET 1,1 COMMENTS From Artur Jasinski, 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] LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 MATHEMATICA a = {}; Do[If[EulerPhi[x]/x == 24/35, AppendTo[a, x]], {x, 1, 10000}]; a (* Artur Jasinski, Nov 09 2008 *) Take[With[{nn=10}, Sort[Flatten[Table[5^i 7^j, {i, nn}, {j, nn}]]]], 40] (* Harvey P. Dale, Feb 09 2013 *) 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 CROSSREFS Cf. A003595, A147571-A147575, A147576-A147580 [From Artur Jasinski, Nov 09 2008] Cf. A033845, A033846, A033847, A033848, A033849, A033850. Subsequence of A256617. Sequence in context: A228453 A327651 A319042 * A219825 A194716 A220047 Adjacent sequences:  A033848 A033849 A033850 * A033852 A033853 A033854 KEYWORD nonn AUTHOR EXTENSIONS Offset fixed by Reinhard Zumkeller, Sep 13 2011 STATUS approved

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Last modified December 3 20:35 EST 2020. Contains 338920 sequences. (Running on oeis4.)