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 A331580 Smallest number whose unsorted prime signature is the reversed unsorted prime signature of n. 3

%I

%S 1,2,2,4,2,6,2,8,4,6,2,18,2,6,6,16,2,12,2,18,6,6,2,54,4,6,8,18,2,30,2,

%T 32,6,6,6,36,2,6,6,54,2,30,2,18,18,6,2,162,4,12,6,18,2,24,6,54,6,6,2,

%U 150,2,6,18,64,6,30,2,18,6,30,2,108,2,6,12,18,6

%N Smallest number whose unsorted prime signature is the reversed unsorted prime signature of n.

%C Unsorted prime signature (A124010) is the sequence of exponents in a number's prime factorization.

%e The prime signature of 12345678 = 2*3*3*47*14593 is (1,2,1,1), and the least number with prime signature (1,1,2,1) is 1050 = 2*3*5*5*7, so a(12345678) = 1050.

%t ptnToNorm[y_]:=Join@@Table[ConstantArray[i,y[[i]]],{i,Length[y]}];

%t Table[Times@@Prime/@ptnToNorm[Reverse[Last/@If[n==1,{},FactorInteger[n]]]],{n,100}]

%Y The range is A055932.

%Y The non-reversed version is A071364.

%Y Unsorted prime signature is A124010.

%Y Numbers whose prime signature is aperiodic are A329139.

%Y Cf. A056239, A112798, A233249, A333217, A333219, A334032, A334033.

%K nonn

%O 1,2

%A _Gus Wiseman_, Apr 18 2020

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Last modified September 26 11:48 EDT 2020. Contains 337371 sequences. (Running on oeis4.)