This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A279288 #21 Jun 22 2025 15:18:16
%S A279288 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,
%T A279288 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,
%U A279288 1,1,1,1,1,1,3,1,1,1,1,5,5,1,1,1,1,2,1
%N A279288 a(n) = denominator of (phi(n)/tau(n)).
%C A279288 a(n) = denominator of (A000010(n)/A000005(n)).
%C A279288 See A279287 (numerator of (phi(n)/tau(n))) and A063070 (phi(n)-tau(n)).
%C A279288 a(n) = 1 and A279287(n) = 1 for numbers n in A020488; A279287(n) > a(n) for numbers n in A279289.
%H A279288 Jaroslav Krizek, <a href="/A279288/b279288.txt">Table of n, a(n) for n = 1..1000</a>
%F A279288 a(n) = 1 for numbers in A020491.
%e A279288 For n = 6: phi(6)/tau(6) = 2/4 = 1/2; a(6) = 2.
%t A279288 Table[Denominator[EulerPhi[n]/DivisorSigma[0, n]], {n, 120}] (* _Michael De Vlieger_, Dec 10 2016 *)
%o A279288 (Magma) [Denominator(EulerPhi(n)/NumberOfDivisors(n)): n in[1..1000]];
%o A279288 (PARI) a(n) = denominator(eulerphi(n)/numdiv(n)) \\ _Felix Fröhlich_, Dec 09 2016
%Y A279288 Cf. A000005, A000010, A020488, A020490, A020491, A063070, A279287, A279289.
%K A279288 nonn,frac
%O A279288 1,2
%A A279288 _Jaroslav Krizek_, Dec 09 2016