A279287 - OEIS

%I #18 Sep 08 2022 08:46:18

%S 1,1,1,2,2,1,3,1,2,1,5,2,6,3,2,8,8,1,9,4,3,5,11,1,20,3,9,2,14,1,15,8,

%T 5,4,6,4,18,9,6,2,20,3,21,10,4,11,23,8,14,10,8,4,26,9,10,3,9,7,29,4,

%U 30,15,6,32,12,5,33,16,11,3,35,2,36,9,20,6,15,3

%N a(n) = numerator of (phi(n)/tau(n)).

%C a(n) = numerator of (A000010(n)/A000005(n)).

%C See A279288 (denominator of (phi(n)/tau(n))) and A063070 (phi(n)-tau(n)).

%C a(n) = 1 and A279288(n) = 1 for numbers n in A020488; a(n) > A279288(n) for numbers n in A279289.

%H Jaroslav Krizek, <a href="/A279287/b279287.txt">Table of n, a(n) for n = 1..1000</a>

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

%p with(numtheory): A279287:=n->numer(phi(n)/sigma(n)): seq(A279287(n), n=1..150); # _Wesley Ivan Hurt_, Dec 11 2016

%t Table[Numerator[EulerPhi[n]/DivisorSigma[0, n]], {n, 78}] (* _Michael De Vlieger_, Dec 09 2016 *)

%o (Magma) [Numerator(EulerPhi(n)/NumberOfDivisors(n)): n in[1..1000]]

%o (PARI) a(n) = numerator(eulerphi(n)/numdiv(n)) \\ _Felix Fröhlich_, Dec 09 2016

%Y Cf. A000005, A000010, A020488, A020490, A020491, A063070, A279288, A279289.

%K nonn,frac

%O 1,4

%A _Jaroslav Krizek_, Dec 09 2016