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A085232 In canonical prime factorization: power of smallest prime factor is less than power of greatest prime factor. 3

%I #8 Jul 30 2018 17:51:00

%S 6,10,14,15,18,20,21,22,26,28,30,33,34,35,36,38,39,42,44,46,50,51,52,

%T 54,55,57,58,60,62,65,66,68,69,70,72,74,75,76,77,78,82,84,85,86,87,88,

%U 90,91,92,93,94,95,98,99,100,102,104,105,106,108,110,111,114,115

%N In canonical prime factorization: power of smallest prime factor is less than power of greatest prime factor.

%C A028233(a(n)) < A053585(a(n));

%C p*a(n) is a term for all primes p with A020639(a(n))<p < A006530(a(n));

%C a(n)=A057714(n-1) for n<28: a(28)=60, A057714(28-1)=62.

%H Harvey P. Dale, <a href="/A085232/b085232.txt">Table of n, a(n) for n = 1..2500</a>

%e 60 = 2^2 * 3 * 5 with 2^2=4 < 5, therefore 60 is a term.

%t spfQ[n_]:=Module[{fi=FactorInteger[n]},Length[fi]>1&&fi[[1,1]]^fi[[1,2]] < fi[[-1,1]]^fi[[-1,2]]]; Select[Range[120],spfQ] (* _Harvey P. Dale_, Jul 30 2018 *)

%Y Cf. A085231.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Jun 22 2003

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Last modified April 23 20:27 EDT 2024. Contains 371916 sequences. (Running on oeis4.)