%I #9 Sep 08 2022 08:46:09

%S 1,2,6,12,10,2,14,8,9,10,22,3,26,14,20,80,34,6,38,30,84,22,46,2,75,26,

%T 108,3,58,20,62,96,44,34,140,36,74,38,156,4,82,28,86,33,30,46,94,60,

%U 147,150,68,78,106,36,220,7,228,58,118,5,122,62,126,448,260

%N Denominator of (n/tau(n) + sigma(n)/n)

%C Denominator of (n/A000005(n) + A000203(n)/n).

%C See A245784 - numerator of (n/tau(n) + sigma(n)/n).

%C A245784(n) / a(n) = integer for numbers n in A245786; a(n) = 1.

%C First deviation from A245777 (denominator of (n/tau(n) - sigma(n)/n)) is at a(300); a(300) = 25, A245777(300) = 75. Sequence of numbers n such that A245777(n) is not equal to a(n): 300, 768, 1452, 1764, 2100, 3468, 3900, 5376, 5700, 6084, 6348, 9075, 9300, ... See (Magma) [n: n in [1..10000] | (Denominator((n/(#[d: d in Divisors(n)]))+(SumOfDivisors(n)/n))) - (Denominator((n/(#[d: d in Divisors(n)]))-(SumOfDivisors(n)/n))) ne 0]

%H Jaroslav Krizek, <a href="/A245785/b245785.txt">Table of n, a(n) for n = 1..10000</a>

%e For n = 9; a(9) = denominator(9/tau(9) + sigma(9)/9) = denominator(9/3 + 13/9) = denominator(40/9) = 9.

%o (Magma) [Denominator((n/(#[d: d in Divisors(n)]))+(SumOfDivisors(n)/n)): n in [1..1000]]

%o (PARI) for(n=1, 100, s=n/numdiv(n); t=sigma(n)/n; print1(denominator(s+t),", ")) \\ _Derek Orr_, Aug 15 2014

%Y Cf. A000005, A000203, A245784, A245786.

%K nonn,frac

%O 1,2

%A _Jaroslav Krizek_, Aug 15 2014