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A161888
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a(n) = the smallest positive integer that does not divide n, and is such that sum{k=1 to n} a(k) is coprime to n.
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2
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2, 3, 2, 6, 3, 7, 2, 6, 4, 4, 2, 8, 2, 4, 4, 6, 2, 4, 2, 6, 4, 4, 2, 14, 3, 3, 4, 8, 2, 4, 2, 6, 2, 4, 2, 8, 2, 4, 4, 6, 2, 4, 2, 6, 6, 4, 2, 10, 2, 4, 2, 6, 2, 4, 3, 3, 4, 4, 2, 8, 2, 4, 4, 6, 3, 5, 2, 6, 2, 8, 2, 10, 2, 4, 4, 6, 3, 9, 2, 6, 4, 4, 2, 8, 3, 3, 4, 6, 2, 4, 2, 6, 4, 4, 3, 5, 2, 4, 2, 8, 2, 8, 2, 6, 2
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OFFSET
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1,1
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COMMENTS
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LINKS
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MATHEMATICA
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spi[{n_, s_, a_}]:=Module[{k=1}, While[Divisible[n+1, k]||!CoprimeQ[s+k, n+1], k++]; {n+1, s+k, k}]; Transpose[NestList[spi, {1, 2, 2}, 105]][[3]] (* Harvey P. Dale, May 26 2015 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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