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Search: id:A124386
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| A124386 |
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For all n>=2, sum{2<=k<=n, GCD(k,n)>1} a(k) = n. a(1)=1. |
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+0
2
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| 1, 2, 3, 2, 5, -1, 7, 5, 7, -3, 11, -3, 13, 5, 7, 9, 17, -15, 19, 7, 11, 3, 23, -15, 9, 17, 33, -3, 29, -55, 31, 77, 47, -15, 45, -89, 37, 91, 79, -45, 41, -171, 43, 183, 189, 37, 47, -351, 155, 123, 373, 165, 53, -655, -471, 533, 553, 191, 59, -859, 61, 861, 233, 33, 839, -1073, 67, 687, 1761, -637, 71
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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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) = 12.
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MATHEMATICA
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f[n_] := Select[Range[2, n], GCD[ #, n] > 1 &]; g[l_] := Block[{n = Length[l] + 1}, Append[l, n - Plus @@ l[[Most[f[n]]]]]]; Nest[g, {1}, 70] (*Chandler*)
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CROSSREFS
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Cf. A124385.
Sequence in context: A157449 A127705 A053139 this_sequence A098668 A112763 A093476
Adjacent sequences: A124383 A124384 A124385 this_sequence A124387 A124388 A124389
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KEYWORD
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sign
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AUTHOR
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Leroy Quet 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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