A090387 Numerator of d(n)/n, where d(n) (A000005) is the number of divisors of n.
1, 1, 2, 3, 2, 2, 2, 1, 1, 2, 2, 1, 2, 2, 4, 5, 2, 1, 2, 3, 4, 2, 2, 1, 3, 2, 4, 3, 2, 4, 2, 3, 4, 2, 4, 1, 2, 2, 4, 1, 2, 4, 2, 3, 2, 2, 2, 5, 3, 3, 4, 3, 2, 4, 4, 1, 4, 2, 2, 1, 2, 2, 2, 7, 4, 4, 2, 3, 4, 4, 2, 1, 2, 2, 2, 3, 4, 4, 2, 1, 5, 2, 2, 1, 4, 2, 4, 1, 2, 2, 4, 3, 4, 2, 4, 1, 2, 3, 2, 9, 2, 4, 2, 1, 8
Offset: 1
Examples
a(6)=2 because the number of divisors of 6 is 4 and 4 divided by 6 equals 2/3, which has 2 as its numerator.
Links
- Antti Karttunen, Table of n, a(n) for n = 1..65537
Programs
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Maple
with(numtheory): seq(numer(tau(n)/n), n=1..105) ; # Zerinvary Lajos, Jun 04 2008
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PARI
A090387(n) = numerator(numdiv(n)/n); \\ Antti Karttunen, Sep 25 2018
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Python
from math import gcd from sympy import divisor_count def A090387(n): return (d := divisor_count(n))//gcd(n,d) # Chai Wah Wu, Jun 20 2022
Extensions
More terms from Robert G. Wilson v, Feb 04 2004
Comments