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A123302
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a(0) = 1. a(n) = the n-th integer from among those positive integers coprime to a(n-1).
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1
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1, 1, 2, 5, 4, 9, 8, 13, 8, 17, 10, 27, 17, 13, 15, 28, 37, 17, 19, 20, 49, 24, 65, 31, 24, 73, 26, 57, 44, 63, 52, 67, 32, 65, 46, 73, 36, 109, 38, 81, 59, 41, 43, 44, 95, 59, 46, 97, 48, 145, 64, 101, 52, 113, 54, 163, 56, 131, 58, 121, 65, 82, 127, 63, 110, 177, 100, 167, 68
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OFFSET
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0,3
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LINKS
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EXAMPLE
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The positive integers coprime to a(6)=8 are 1,3,5,7,9,11,13,15,17,19... The seventh of these is 13, so a(7) = 13.
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MATHEMATICA
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f[l_List] := Block[{k = 0, c = Length[l]}, While[c > 0, k++; While[ GCD[k, l[[ -1]]] > 1, k++ ]; c--; ]; Append[l, k]]; Nest[f, {1}, 70] (* Ray Chandler, Nov 11 2006 *)
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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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