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A117818 a(n) = n if n is 1 or a prime, otherwise a(n) = n divided by the least prime factor of n (A032742(n)). 3
1, 2, 3, 2, 5, 3, 7, 4, 3, 5, 11, 6, 13, 7, 5, 8, 17, 9, 19, 10, 7, 11, 23, 12, 5, 13, 9, 14, 29, 15, 31, 16, 11, 17, 7, 18, 37, 19, 13, 20, 41, 21, 43, 22, 15, 23, 47, 24, 7, 25, 17, 26, 53, 27, 11, 28, 19, 29, 59, 30, 61, 31, 21, 32, 13, 33, 67, 34, 23, 35, 71, 36, 73, 37, 25, 38 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A026741 generalized to give either a prime or the largest proper divisor of a nonprime.

Sometimes called "Conway's subprime function", although it surely predates John Conway. - N. J. A. Sloane, Sep 29 2017

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

MATHEMATICA

Table[If[PrimeQ[n], n, If[n == 1, 1, n/FactorInteger[n][[1, 1]]]], {n, 1, 76}]

PROG

(Haskell)

a117818 n = if a010051 n == 1 then n else a032742 n

-- Reinhard Zumkeller, Jun 24 2013

CROSSREFS

Cf. A026741, A032742, A292772.

Sequence in context: A095163 A033677 A116548 * A073890 A079311 A060474

Adjacent sequences:  A117815 A117816 A117817 * A117819 A117820 A117821

KEYWORD

nonn,easy

AUTHOR

Roger L. Bagula, Apr 30 2006

EXTENSIONS

Edited by Stefan Steinerberger, Jul 22 2007

Extended by Charles R Greathouse IV, Jul 28 2010

STATUS

approved

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Last modified December 17 14:12 EST 2018. Contains 318201 sequences. (Running on oeis4.)