This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A375080 #11 Jul 31 2024 01:33:03
%S A375080 0,1,1,5,2,3,3,17,14,11,5,22,6,8,9,49,8,23,9,13,13,13,11,33,44,31,17,
%T A375080 56,14,21,15,43,21,41,23,233,18,23,25,115,20,30,21,30,32,28,23,178,30,
%U A375080 69,33,107,26,39,37,41,37,71,29,46,30,38,137,321,44,48,33,47,45,52
%N A375080 a(n) is the numerator of ( Sum_{d|n} (n - d) )/tau(n).
%C A375080 ( Sum_{d|n} (n - d) )/tau(n) is the average distance between n and its divisor.
%F A375080 a(n) = numerator((n - sigma(n))/tau(n)).
%F A375080 a(n) = numerator(n - A000203(n)/A000005(n)).
%F A375080 a(n) = numerator(n - A057020(n)/A057021(n)).
%t A375080 a[n_]:=Numerator[n-DivisorSigma[1,n]/DivisorSigma[0,n]]; Array[a,70]
%o A375080 (Python)
%o A375080 from math import prod
%o A375080 from fractions import Fraction
%o A375080 from sympy import factorint
%o A375080 def A375080(n):
%o A375080 f = factorint(n).items()
%o A375080 return (n-Fraction(prod((p**(e+1)-1)//(p-1) for p, e in f),prod(e+1 for p,e in f))).numerator # _Chai Wah Wu_, Jul 30 2024
%Y A375080 Cf. A000005, A000203, A057020, A057021 (denominator).
%K A375080 nonn,frac
%O A375080 1,4
%A A375080 _Stefano Spezia_, Jul 29 2024