OFFSET
1,2
COMMENTS
See A245784 - numerator of (n/tau(n) + sigma(n)/n).
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]
LINKS
Jaroslav Krizek, Table of n, a(n) for n = 1..10000
EXAMPLE
For n = 9; a(9) = denominator(9/tau(9) + sigma(9)/9) = denominator(9/3 + 13/9) = denominator(40/9) = 9.
PROG
(Magma) [Denominator((n/(#[d: d in Divisors(n)]))+(SumOfDivisors(n)/n)): n in [1..1000]]
(PARI) for(n=1, 100, s=n/numdiv(n); t=sigma(n)/n; print1(denominator(s+t), ", ")) \\ Derek Orr, Aug 15 2014
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Jaroslav Krizek, Aug 15 2014
STATUS
approved