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Search: id:A124385
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| A124385 |
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For all n>=2, sum{2<=k<=n, GCD(k,n)>1} a(k) = 1. a(1)=1. |
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+0
2
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| 1, 1, 1, 0, 1, -1, 1, 1, 1, -1, 1, -1, 1, 1, 1, 1, 1, -3, 1, 1, 1, 1, 1, -3, -1, 3, 5, -1, 1, -7, 1, 9, 5, -1, 5, -13, 1, 13, 11, -5, 1, -25, 1, 25, 29, 5, 1, -53, 19, 19, 53, 23, 1, -95, -73, 81, 81, 25, 1, -119, 1, 119, 27, 1, 113, -143, 1, 89, 243, -69, 1, -335, 1, 457, 351, -81, 145, -841, 1, 497, 831, 425, 1, -1809, -883, 1809
(list; graph; listen)
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OFFSET
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1,18
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EXAMPLE
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The positive integers which are <= 12 and are not coprime to 12 are 2,3,4,6,8,9, 10,12. And a(12) is such that a(2)+a(3)+a(4)+a(6)+a(8)+a(9)+a(10)+a(12) = 1.
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MATHEMATICA
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f[n_] := Select[Range[2, n], GCD[ #, n] > 1 &]; g[l_] :=Append[l, 1 - Plus @@ l[[Most[f[Length[l] + 1]]]]]; Nest[g, {1}, 85] (*Chandler*)
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CROSSREFS
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Cf. A124386.
Adjacent sequences: A124382 A124383 A124384 this_sequence A124386 A124387 A124388
Sequence in context: A014491 A061680 A097558 this_sequence A106478 A115069 A046556
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KEYWORD
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sign
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Oct 29 2006
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 13 2006
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