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A071888
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a(1)=2 and for n>1 a(n) = least squarefree m > n with gcd(m,n)>1.
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5
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2, 6, 6, 6, 10, 10, 14, 10, 15, 14, 22, 14, 26, 21, 21, 22, 34, 21, 38, 22, 30, 26, 46, 26, 30, 30, 30, 30, 58, 33, 62, 34, 39, 38, 42, 38, 74, 42, 42, 42, 82, 46, 86, 46, 51, 58, 94, 51, 70, 55, 57, 58, 106, 57, 65, 58, 66, 62, 118, 62, 122, 66, 66, 66
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| A071889(n)=gcd(a(n),n); A071890(n)=a(n)-n;
For n>2: n is prime iff a(n)=n*2.
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MATHEMATICA
| a[1] = 2; a[n_] := a[n] = (m = n+1; While[ !(SquareFreeQ[m] && GCD[m, n] > 1), m++]; m); Table[a[n], {n, 1, 64}] (* From Jean-François Alcover, Feb 15 2012 *)
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CROSSREFS
| Cf. A005117, A071891, A071892.
Sequence in context: A103643 A079892 A096014 * A117217 A161331 A120627
Adjacent sequences: A071885 A071886 A071887 * A071889 A071890 A071891
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KEYWORD
| nonn,nice,changed
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jun 10 2002
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