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A112399
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a(n) = sum{1<=k<=n, GCD(k,n)=1} mu(k), where mu(k) = A008683(k) (the Moebius function).
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1
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1, 1, 0, 0, -1, 0, -1, -2, -2, -1, -1, -2, -2, -3, -2, -3, -1, -4, -2, -5, -4, -3, -1, -6, -3, -4, -3, -5, -1, -6, -3, -7, -5, -5, -3, -7, -1, -5, -3, -6, 0, -9, -2, -7, -6, -6, -2, -11, -4, -9, -5, -7, -2, -12, -5, -8, -5, -5, 0, -13, -1, -7, -6, -8, -4, -12, -1, -8, -5, -10, -2, -14, -3, -8, -9, -9, -4, -14, -3, -12, -7, -8, -3, -17
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,8
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EXAMPLE
| The positive integers <= 10 and coprime to 10 are 1, 3, 7 and 9. So a(10) = mu(1) + mu(3) + mu(7) + mu(9) = 1 - 1 - 1 + 0 = -1.
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MATHEMATICA
| quetMu[n_] := Sum[KroneckerDelta[GCD[i, n], 1] MoebiusMu[i], {i, n}]; Table[quetMu[n], {n, 85}] (* Alonso del Arte, Nov 28 2011 *)
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PROG
| (PARI) a(n)=sum(k=1, n, if(gcd(n, k)==1, moebius(k), 0)) \\ Herrgesell
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CROSSREFS
| Cf. A008683.
Sequence in context: A160418 A168115 A153864 * A165123 A106180 A055091
Adjacent sequences: A112396 A112397 A112398 * A112400 A112401 A112402
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KEYWORD
| sign
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AUTHOR
| Leroy Quet Dec 06 2005
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EXTENSIONS
| More terms from Lambert Herrgesell and Matthew Conroy, Dec 09 2005
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