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 A085393 Difference between the largest and the smallest prime factor of the greatest proper divisor of n. 3
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,20 LINKS Antti Karttunen, Table of n, a(n) for n = 1..16384 FORMULA a(n) = A085392(n) - A014673(n). MATHEMATICA 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 *) CROSSREFS Cf. A014673, A085392. Sequence in context: A348071 A204060 A359780 * A128980 A096693 A193139 Adjacent sequences: A085390 A085391 A085392 * A085394 A085395 A085396 KEYWORD nonn AUTHOR Robert G. Wilson v and Reinhard Zumkeller, Jun 26 2003 STATUS approved

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Last modified March 31 15:44 EDT 2023. Contains 361668 sequences. (Running on oeis4.)