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A124406
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For n>=2, n = sum{n/2<=k<=n, GCD(k,n)=1} a(k).
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1
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2, 3, 4, 1, 6, 0, 2, 1, 8, 0, 10, -8, -4, 8, 2, 1, 12, -2, 2, 0, 10, 2, 14, -18, -14, 2, 12, 6, 2, 2, -6, 15, 14, -2, 38, -42, -32, 16, 26, -4, 78, -66, -74, 26, 2, 66, 56, -94, -26, -112, -12, 164, 18, -38, -16, -134, -8, 204, 46, -42, -48, -338, 2, 453, 10, -50, -4, -252, 24, 272, 64, -104, -64, -176, -6, 242, 48, -28, -20, -402
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| The integers which are >= 9/2 and are < 9 and are coprime to 9 are 5,7,8. So a(5) + a(7) + a(8) = 9.
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MATHEMATICA
| f[n_] := Select[Range[Ceiling[n/2], n], GCD[ #, n] == 1 &]; g[l_] := Block[{n = Length[l] + 2}, Append[l, n - Plus @@ l[[Most[f[n]]]]]]; Nest[g, {}, 80] (*Chandler*)
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CROSSREFS
| Cf. A124407.
Sequence in context: A117386 A101174 A050144 * A065331 A066262 A174715
Adjacent sequences: A124403 A124404 A124405 * A124407 A124408 A124409
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KEYWORD
| sign
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AUTHOR
| Leroy Quet Oct 31 2006
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EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 13 2006
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