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A068101 a(n) = Sum_{k|n, k<=sqrt(n)} mu(k) where mu(k) is the Moebius function and the sum is over the positive divisors k of n with k <= sqrt(n). 3
1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0, 1, -1, 0, 0, 0, 0, 1, -2, 1, 0, 0, 0, 0, 0, 1, 0, 0, -1, 1, 0, 1, 0, -1, 0, 1, 0, 0, -1, 0, 0, 1, 0, 0, -1, 0, 0, 1, -1, 1, 0, -1, 0, 0, 0, 1, 0, 0, -2, 1, 0, 1, 0, -1, 0, 0, 0, 1, -1, 0, 0, 1, -1, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 1, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,30

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = Sum_{k=1..A038548(n)} A008683(A161906(n,k)). - Reinhard Zumkeller, Jul 30 2013

G.f.: Sum_{k>=1} mu(k)*x^(k^2)/(1 - x^k). - Ilya Gutkovskiy, Jan 03 2017

MATHEMATICA

Table[DivisorSum[n, MoebiusMu, # <= Sqrt[n] &], {n, 103}] (* Michael De Vlieger, Sep 24 2017 *)

PROG

(Haskell)

a068101 = sum . map a008683 . a161906_row

-- Reinhard Zumkeller, Jul 30 2013

(PARI) a(n) = sumdiv(n, k, (k<=sqrt(n))*moebius(k)); \\ Michel Marcus, Jan 03 2017

CROSSREFS

Cf. A086956.

Sequence in context: A263774 A161519 A286561 * A094263 A049761 A211225

Adjacent sequences:  A068098 A068099 A068100 * A068102 A068103 A068104

KEYWORD

sign

AUTHOR

Leroy Quet, Mar 22 2002

STATUS

approved

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Last modified August 24 03:51 EDT 2019. Contains 326260 sequences. (Running on oeis4.)