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A085393
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Difference between the largest and the smallest prime factor of the greatest proper divisor of n.
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3
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 1, 0, 0, 0, 5, 0, 2, 0, 0, 0, 0, 0, 1, 0, 0, 0, 3, 0, 4, 0, 9, 2, 0, 0, 1, 0, 0, 0, 11, 0, 0, 0, 5, 0, 0, 0, 3, 0, 0, 4, 0, 0, 8, 0, 15, 0, 2, 0, 1, 0, 0, 0, 17, 0, 10, 0, 3, 0, 0, 0, 5, 0, 0, 0, 9, 0, 2, 0, 21, 0, 0, 0, 1, 0, 0, 8, 3, 0, 14
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OFFSET
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1,20
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LINKS
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Antti Karttunen, Table of n, a(n) for n = 1..16384
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FORMULA
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a(n) = A085392(n) - A014673(n).
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MATHEMATICA
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PrimeFactors[n_] := Flatten[ Table[ # [[1]], {1}] & /@ FactorInteger[n]]; f[n_] := Block[{gpd = Divisors[n][[ -2]]}, If[gpd == 1, 0, PrimeFactors[gpd][[ -1]] - PrimeFactors[gpd][[1]] ]]; Table[ If[n == 1, 0, f[n]], {n, 1, 102}]
{1}~Join~Array[#[[-1, 1]] - #[[1, 1]] &@ FactorInteger@ Last@ Most@ Divisors@ # &, 101, 2] (* Michael De Vlieger, Dec 03 2017 *)
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CROSSREFS
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Cf. A014673, A085392.
Sequence in context: A348071 A204060 A359780 * A128980 A096693 A193139
Adjacent sequences: A085390 A085391 A085392 * A085394 A085395 A085396
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KEYWORD
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nonn
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AUTHOR
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Robert G. Wilson v and Reinhard Zumkeller, Jun 26 2003
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STATUS
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approved
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