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A087802 Sum(mu(d): d nonprime divisor of n), mu=A008683. 2
1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 2, 1, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 1, 2, 2, 2, 2, 1, 2, 2, 2, 1, 3, 1, 2, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 3, 1, 2, 2, 1, 2, 3, 1, 2, 2, 3, 1, 2, 1, 2, 2, 2, 2, 3, 1, 2, 1, 2, 1, 3, 2, 2, 2, 2, 1, 3, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 1, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

COMMENTS

A064372 and this sequence first differ at term 64: A064372(64)=2 and a(64)=1. - Rick L. Shepherd, Mar 07 2004

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = if n=1 then 1 else A001221(n). - Vladeta Jovovic, Oct 17 2003

EXAMPLE

Divisors of n=42: {1,2,3,6,7,14,21,42}, a(42) = mu(1)+mu(6)+mu(14)+mu(21)+mu(42) = 1+1+1+1-1 = 3.

MATHEMATICA

Table[Total[MoebiusMu[#]&/@Select[Divisors[n], !PrimeQ[#]&]], {n, 120}] (* Harvey P. Dale, Oct 14 2014 *)

PROG

(PARI) A087802(n) = sumdiv(n, d, if(!isprime(d), moebius(d)))

CROSSREFS

Cf. A023890, A033273. Different from A079553.

Sequence in context: A293460 A231813 A158210 * A079553 A001221 A064372

Adjacent sequences:  A087799 A087800 A087801 * A087803 A087804 A087805

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Oct 11 2003

STATUS

approved

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Last modified October 20 17:24 EDT 2018. Contains 316392 sequences. (Running on oeis4.)