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 A147516 List giving least odd integer of each prime signature. 5
 1, 3, 9, 15, 27, 45, 81, 105, 135, 225, 243, 315, 405, 675, 729, 945, 1155, 1215, 1575, 2025, 2187, 2835, 3375, 3465, 3645, 4725, 6075, 6561, 8505, 10125, 10395, 10935, 11025, 14175, 15015, 17325, 18225, 19683, 23625, 25515, 30375, 31185, 32805 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS All numbers of the form 3^k2*5^k3*...*p_n^k_n, where k2 >= k3 >= ... >= k_n, sorted. LINKS Ray Chandler, Table of n, a(n) for n = 1..10000 David Ryan, Mathematical Harmony Analysis, arXiv preprint arXiv:1603.08904 [cs.SD], 2016. MATHEMATICA PrimeExponents[n_] := FactorInteger[n][[All, 2]]; lpe = {}; A147516 = {1}; Do[pe = PrimeExponents[n] // Sort; If[FreeQ[lpe, pe], AppendTo[lpe, pe]; AppendTo[A147516, n]], {n, 3, 40000, 2}]; A147516 (* Jean-François Alcover, Jan 27 2015, after Robert G. Wilson v *) PROG (PARI) is(n)=my(k=oo, t); forprime(p=3, , t=valuation(n, p); if(t>k, return(0), k=t); if(k, n/=p^k, return(n==1))) \\ Charles R Greathouse IV, Aug 20 2015 CROSSREFS Cf. A025487. Sequence in context: A287351 A256388 A082897 * A233819 A131822 A131801 Adjacent sequences:  A147513 A147514 A147515 * A147517 A147518 A147519 KEYWORD nonn AUTHOR Will Nicholes, Nov 05 2008 EXTENSIONS Edited and extended by Ray Chandler, Jul 29 2010 STATUS approved

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