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A322655
Numerator of (Sum_{d|n} sigma(d)) / sigma(n).
3
1, 4, 5, 11, 7, 5, 9, 26, 18, 14, 13, 55, 15, 3, 35, 57, 19, 24, 21, 11, 45, 13, 25, 13, 38, 10, 29, 99, 31, 35, 33, 40, 65, 38, 21, 198, 39, 7, 75, 91, 43, 15, 45, 143, 21, 25, 49, 285, 22, 152, 95, 165, 55, 29, 91, 39, 21, 62, 61, 55, 63, 11, 81, 247, 5, 65
OFFSET
1,2
COMMENTS
Numerator of A007429(n) / A000203(n).
Also numerator of Sum_{d|n} (sigma(d) / sigma(n)).
LINKS
FORMULA
a(n) = A007429(n) / gcd(A000203(n), A007429(n)). - Antti Karttunen, Nov 15 2021
EXAMPLE
For n = 4; a(4) = numerator((Sum_{d|4} sigma(d)) / sigma(4)) = numerator((1 + 3 + 7) / (1 + 2 + 4)) = numerator(11/7) = 11.
MATHEMATICA
Table[Numerator[Sum[DivisorSigma[1, d], {d, Divisors[n]}] / DivisorSigma[1, n]], {n, 1, 100}] (* Vaclav Kotesovec, Dec 22 2018 *)
PROG
(Magma) [Numerator(&+[SumOfDivisors(d): d in Divisors(n)] / SumOfDivisors(n)): n in [1..1000]]
(PARI) a(n) = numerator(sumdiv(n, d, sigma(d))/sigma(n)); \\ Michel Marcus, Dec 22 2018
CROSSREFS
Cf. A000203, A007429, A319296, A221219, A322656 (denominator).
Sequence in context: A295656 A126069 A147559 * A206028 A007429 A064945
KEYWORD
nonn,frac
AUTHOR
Jaroslav Krizek, Dec 22 2018
STATUS
approved