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A036490 Numbers whose prime factors are in {5, 7, 11}. 3
5, 7, 11, 25, 35, 49, 55, 77, 121, 125, 175, 245, 275, 343, 385, 539, 605, 625, 847, 875, 1225, 1331, 1375, 1715, 1925, 2401, 2695, 3025, 3125, 3773, 4235, 4375, 5929, 6125, 6655, 6875, 8575, 9317, 9625, 12005, 13475, 14641, 15125, 15625, 16807 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

G. E. Andrews, The Theory of Partitions, Addison-Wesley, 1976, p. 160.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[Range[20000], (fi = FactorInteger[#][[All, 1]]; Intersection[fi, {5, 7, 11}] == fi)&]

(* or, for a large number of terms: *)

f[pp_(* primes *), max_(* maximum term *)] := Module[{a, aa, k, iter}, k = Length[pp]; aa = Array[a, k]; iter = Table[{a[j], 0, PowerExpand @ Log[pp[[j]], max/Times @@ (Take[pp, j-1]^Take[aa, j-1])]}, {j, 1, k}]; Table[Times @@ (pp^aa), Sequence @@ iter // Evaluate] // Flatten // Sort]; A036490 = f[{5, 7, 11}, 2*10^14] // Rest (* Jean-François Alcover, Sep 19 2012, updated Nov 12 2016 *)

PROG

(Haskell)

import Data.Set (Set, fromList, insert, deleteFindMin)

a036490 n = a036490_list !! (n-1)

a036490_list = f $ fromList [5, 7, 11] where

   f s = m : (f $ insert (5 * m) $ insert (7 * m) $ insert (11 * m) s')

         where (m, s') = deleteFindMin s

-- Reinhard Zumkeller, Feb 19 2013

CROSSREFS

Cf. A036491, A036492.

Sequence in context: A218394 A067289 A036491 * A106330 A057247 A157437

Adjacent sequences:  A036487 A036488 A036489 * A036491 A036492 A036493

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard

EXTENSIONS

Offset corrected by Reinhard Zumkeller, Feb 19 2013

STATUS

approved

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Last modified June 25 12:02 EDT 2017. Contains 288710 sequences.