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 A331580 Smallest number whose unsorted prime signature is the reversed unsorted prime signature of n. 3
 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, 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, 150, 2, 6, 18, 64, 6, 30, 2, 18, 6, 30, 2, 108, 2, 6, 12, 18, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Unsorted prime signature (A124010) is the sequence of exponents in a number's prime factorization. LINKS EXAMPLE 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. MATHEMATICA ptnToNorm[y_]:=Join@@Table[ConstantArray[i, y[[i]]], {i, Length[y]}]; Table[Times@@Prime/@ptnToNorm[Reverse[Last/@If[n==1, {}, FactorInteger[n]]]], {n, 100}] CROSSREFS The range is A055932. The non-reversed version is A071364. Unsorted prime signature is A124010. Numbers whose prime signature is aperiodic are A329139. Cf. A056239, A112798, A233249, A333217, A333219, A334032, A334033. Sequence in context: A328707 A067824 A107067 * A320389 A046801 A316437 Adjacent sequences:  A331577 A331578 A331579 * A331581 A331582 A331583 KEYWORD nonn AUTHOR Gus Wiseman, Apr 18 2020 STATUS approved

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Last modified August 8 08:27 EDT 2020. Contains 336293 sequences. (Running on oeis4.)