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A295127 Numerator of Sum_{d|n} mu(n/d)/d, where mu is the Möbius function A008683. 2
1, -1, -2, -1, -4, 1, -6, -1, -2, 2, -10, 1, -12, 3, 8, -1, -16, 1, -18, 1, 4, 5, -22, 1, -4, 6, -2, 3, -28, -4, -30, -1, 20, 8, 24, 1, -36, 9, 8, 1, -40, -2, -42, 5, 8, 11, -46, 1, -6, 2, 32, 3, -52, 1, 8, 3, 12, 14, -58, -2, -60, 15, 4, -1, 48, -10, -66, 4, 44, -12 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

First occurrence of k > 0: 1, 10, 14, 21, 22, 26, 116, 15, 38, 164, 46, 57, 212, 58, 62, 390, 1096, 74, 45840, 33, ...;

First occurrence of k < 0: 2, 3, 228, 5, 132, 7, 516, 204, 728, 11, 276, 13, 948, 258, 308, 17, 1236, 19, 5496, 366, ..., .

LINKS

Mats Granvik and Robert G. Wilson v, Table of n, a(n) for n = 1..10000

EXAMPLE

a(6) = 1 since mu(6)/1 + mu(3)/2 + mu(2)/3 + mu(1)/6 = 1 - 1/2 - 1/3 + 1/6 = 1/3.

MAPLE

f:= n -> numer(add(numtheory:-mobius(n/k)/k, k=numtheory:-divisors(n))):

map(f, [$1..100]); # Robert Israel, Nov 16 2017

MATHEMATICA

f[n_] := Block[{d = Divisors@ n}, Plus @@ (MoebiusMu[d]/Reverse@ d)]; Numerator@ Array[f, 70]

PROG

(PARI) a(n) = numerator(sumdiv(n, d, moebius(n/d)/d)); \\ Michel Marcus, Nov 17 2017

CROSSREFS

Cf. A008683, A191898, A007913, A023900, A173557, A295126 (denominator).

Sequence in context: A049559 A063994 A268336 * A076512 A128707 A257022

Adjacent sequences:  A295124 A295125 A295126 * A295128 A295129 A295130

KEYWORD

sign,look

AUTHOR

Mats Granvik and Robert G. Wilson v, Nov 15 2017

STATUS

approved

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Last modified June 6 17:01 EDT 2020. Contains 334829 sequences. (Running on oeis4.)