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A064920
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a(n) = n / gpf(n) + gpf(n) - 1, where gpf = A006530 = greatest prime factor.
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6
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2, 3, 3, 5, 4, 7, 5, 5, 6, 11, 6, 13, 8, 7, 9, 17, 8, 19, 8, 9, 12, 23, 10, 9, 14, 11, 10, 29, 10, 31, 17, 13, 18, 11, 14, 37, 20, 15, 12, 41, 12, 43, 14, 13, 24, 47, 18, 13, 14, 19, 16, 53, 20, 15, 14, 21, 30, 59, 16, 61, 32, 15, 33, 17, 16, 67, 20, 25, 16, 71, 26, 73, 38, 19, 22
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,1
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COMMENTS
| a(n) = A052126(n) + A006530(n) - 1; a(n) <= n and for n > 1: a(n) = n iff n is prime.
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LINKS
| Harry J. Smith, Table of n, a(n) for n=2,...,1000
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EXAMPLE
| a(18) = 18 / 2 + 2 - 1 = 10; a(19) = 19 / 19 + 19 - 1 = 19.
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MATHEMATICA
| a[n_] := (g = FactorInteger[n][[-1, 1]]; n/g + g - 1); a /@ Range[2, 76] (* From Jean-François Alcover, Apr 06 2011 *)
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PROG
| (PARI) gpf(n)= { local(f); f=factor(n)~; return(f[1, length(f)]) } { for (n=2, 1000, g=gpf(n); a=n / g + g - 1; write("b064920.txt", n, " ", a) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 29 2009]
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CROSSREFS
| Cf. A064916, A064921, A064922, A006530, A052126, A064923, A064924.
Sequence in context: A161857 A135533 A119674 * A064916 A062854 A057859
Adjacent sequences: A064917 A064918 A064919 * A064921 A064922 A064923
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KEYWORD
| nice,nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 14 2001
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