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A279288 a(n) = denominator of (phi(n)/tau(n)). 4
1, 2, 1, 3, 1, 2, 1, 1, 1, 1, 1, 3, 1, 2, 1, 5, 1, 1, 1, 3, 1, 2, 1, 1, 3, 1, 2, 1, 1, 1, 1, 3, 1, 1, 1, 3, 1, 2, 1, 1, 1, 2, 1, 3, 1, 2, 1, 5, 1, 3, 1, 1, 1, 4, 1, 1, 1, 1, 1, 3, 1, 2, 1, 7, 1, 2, 1, 3, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 5, 5, 1, 1, 1, 1, 2, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) = denominator of (A000010(n)/A000005(n)).

See A279287 (numerator of (phi(n)/tau(n))) and A063070 (phi(n)-tau(n)).

a(n) = 1 and A279287(n) = 1 for numbers n in A020488; A279287(n) > a(n) for numbers n in A279289.

LINKS

Jaroslav Krizek, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = 1 for numbers in A020491.

EXAMPLE

For n = 6: phi(6)/tau(6) = 2/4 = 1/2; a(6) = 2.

MATHEMATICA

Table[Denominator[EulerPhi[n]/DivisorSigma[0, n]], {n, 120}] (* Michael De Vlieger, Dec 10 2016 *)

PROG

(MAGMA) [Denominator(EulerPhi(n)/NumberOfDivisors(n)): n in[1..1000]]

(PARI) a(n) = denominator(eulerphi(n)/numdiv(n)) \\ Felix Fröhlich, Dec 09 2016

CROSSREFS

Cf. A000005, A000010, A020488, A020490, A020491, A063070, A279287, A279289.

Sequence in context: A035175 A092412 A265578 * A078734 A028293 A092782

Adjacent sequences:  A279285 A279286 A279287 * A279289 A279290 A279291

KEYWORD

nonn,frac

AUTHOR

Jaroslav Krizek, Dec 09 2016

STATUS

approved

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Last modified June 6 18:59 EDT 2020. Contains 334832 sequences. (Running on oeis4.)