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 A088387 Prime corresponding to largest prime power factor of n, a(1)=1. 9
 1, 2, 3, 2, 5, 3, 7, 2, 3, 5, 11, 2, 13, 7, 5, 2, 17, 3, 19, 5, 7, 11, 23, 2, 5, 13, 3, 7, 29, 5, 31, 2, 11, 17, 7, 3, 37, 19, 13, 2, 41, 7, 43, 11, 3, 23, 47, 2, 7, 5, 17, 13, 53, 3, 11, 2, 19, 29, 59, 5, 61, 31, 3, 2, 13, 11, 67, 17, 23, 7, 71, 3, 73, 37, 5, 19, 11, 13, 79, 2, 3, 41, 83, 7, 17 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Most significant prime factor of n: If n = (p_1^e_1)(p_2^e_2)(p_3^e_3)... and max(p_1^e_1,p_2^e_2,...) = p_k^e_k then a(n) = p_k. LINKS Antti Karttunen, Table of n, a(n) for n = 1..65537 FORMULA A034699(n) = a(n)^A088388(n). a(n*a(n)) = a(n). - Sam Alexander, Dec 15 2003 EXAMPLE a(6) = a(2*3) = 3 because 3^1 > 2^1; a(36) = a((2^2)(3^2)) = 3 because 3^2 > 2^2; a(12) = a((2^2)*3) = 2 because 2^2 > 3^1. MATHEMATICA f[n_] := Sort[ {#[[1]]^#[[2]], #[[1]]} & /@ FactorInteger@ n][[ -1, 2]]; Array[f, 85] (* Robert G. Wilson v, Nov 05 2007 *) a[n_] := MaximalBy[FactorInteger[n], Power @@ # &][[1, 1]]; Array[a, 85] (* Jean-François Alcover, Jun 27 2019 *) PROG (PARI) A088387(n) = if(1==n, 1, my(f=factor(n), p=0); isprimepower(vecmax(vector(#f[, 1], i, f[i, 1]^f[i, 2])), &p); (p)); \\ Antti Karttunen, Jul 22 2018 CROSSREFS Cf. A034699, A088388, A307746, A307641. Sequence in context: A273289 A346152 A090662 * A197861 A180506 A273283 Adjacent sequences:  A088384 A088385 A088386 * A088388 A088389 A088390 KEYWORD easy,nonn AUTHOR Reinhard Zumkeller, Sep 28 2003 EXTENSIONS More terms from Ray Chandler, Dec 20 2003 Edited by N. J. A. Sloane at the suggestion of Stefan Steinerberger, Nov 04 2007 STATUS approved

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Last modified November 27 04:53 EST 2021. Contains 349346 sequences. (Running on oeis4.)