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%I #14 Nov 21 2022 09:39:03
%S 1,3,2,1,3,6,4,3,1,9,6,2,7,12,6,1,9,3,10,1,8,18,12,6,1,21,2,4,15,18,
%T 16,3,12,27,12,1,19,6,14,9,21,24,22,2,3,36,24,2,1,1
%N Denominators of antiharmonic means of divisors of n.
%C Numbers k such that sigma_2(k)/sigma_1(k) = A001157(k)/A000203(k) are integers are in A020487.
%H Ivan Neretin, <a href="/A158275/b158275.txt">Table of n, a(n) for n = 1..10000</a>
%F Antiharmonic mean of divisors of number n = Product (p_i^e_i) is sigma_2(n)/sigma_1(n) = A001157(n)/A000203(n) = Product ((p_i^(e_i+1)+1)/(p_i+1)).
%F a(A020487(n)) = 1. - _Amiram Eldar_, Nov 21 2022
%e Antiharmonic means of divisors of n>=1: 1, 5/3, 5/2, 3, 13/2, 25/6, ...
%t Table[Denominator[DivisorSigma[2, n]/DivisorSigma[1, n]], {n, 50}] (* _Ivan Neretin_, May 22 2015 *)
%o (PARI) a(n) = denominator(sigma(n,2)/sigma(n)); \\ _Amiram Eldar_, Nov 21 2022
%Y Cf. A001157, A000203, A020487, A158274 (numerators).
%K nonn,frac
%O 1,2
%A _Jaroslav Krizek_, Mar 15 2009
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