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A127009
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a(1)=1. a(n) = the numerator of the sum of the reciprocals of the earlier terms of the sequence which are coprime to n.
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1
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1, 1, 2, 2, 3, 2, 23, 164, 13389, 243985, 15948790008791, 182889846746034804193, 46520575190667784168670190084854378399767989073, 33107435283268333623593822288321538682200992783751408959931533910313916858227252552270
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OFFSET
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1,3
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LINKS
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EXAMPLE
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The sequence's terms, among terms a(1) through a(7), which are coprime to 8 are a(1)=1, a(2)=1, a(5)=3 and a(7) = 23. So a(8) is the numerator of 1 +1 +1/3 +1/23 = 164/69, which is 164.
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MATHEMATICA
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f[l_List] := Sum[1/l[[k]], {k, Length[l]}]; g[l_List] := Block[{n = Length[l] + 1}, Append[l, Numerator@f[Select[l, GCD[ #, n] == 1 &]]]]; Nest[g, {1}, 13] (* Ray Chandler, Jan 04 2007 *)
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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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