OFFSET
1,8
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.
MATHEMATICA
quetMu[n_] := Sum[KroneckerDelta[GCD[i, n], 1] MoebiusMu[i], {i, n}]; Table[quetMu[n], {n, 85}] (* Alonso del Arte, Nov 28 2011 *)
PROG
(PARI) a(n)=sum(k=1, n, if(gcd(n, k)==1, moebius(k), 0)) \\ Lambert Herrgesell, Dec 09 2005
CROSSREFS
KEYWORD
sign
AUTHOR
Leroy Quet, Dec 06 2005
EXTENSIONS
More terms from Lambert Herrgesell and Matthew Conroy, Dec 09 2005
STATUS
approved