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A117818
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a(n) = n if n is 1 or a prime, otherwise a(n) = n divided by the least prime factor of n (A032742(n)).
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3
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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
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OFFSET
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1,2
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COMMENTS
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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
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LINKS
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MATHEMATICA
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Table[If[PrimeQ[n], n, If[n == 1, 1, n/FactorInteger[n][[1, 1]]]], {n, 1, 76}]
Table[Which[n==1, 1, PrimeQ[n], 1, True, Divisors[n][[-2]]], {n, 80}] (* Harvey P. Dale, Feb 02 2022 *)
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PROG
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(Haskell)
a117818 n = if a010051 n == 1 then n else a032742 n
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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