cp's OEIS Frontend

A276466 a(n) = numerator of Sum_{d|n} 0.d.

%I A276466 #31 Sep 08 2022 08:46:17
%S A276466 1,3,2,7,3,6,4,3,13,9,21,43,23,57,21,83,27,57,29,3,131,63,33,69,17,69,
%T A276466 157,91,39,9,41,99,21,81,33,79,47,87,23,27,51,267,53,147,12,99,57,17,
%U A276466 129,33,27,161,63,309,63,159,29,117,69,357,71,123,71,131,69
%N A276466 a(n) = numerator of Sum_{d|n} 0.d.
%C A276466 Let d be a divisor of n; 0.d means the decimal fraction formed by writing d after the decimal point, e.g., 0.12 = 12/100 = 3/25.
%C A276466 The first few values of Sum_{d|n} 0.d for n = 1,2,.. are 1/10, 3/10, 2/5, 7/10, 3/5, 6/5, 4/5, 3/2, 13/10, 9/10, 21/100, 43/25, ...
%C A276466 16450 is the only number < 5*10^7 such that Sum_{d|n} 0.d is an integer: Sum_{d | 16450} 0.d = 0.1 + 0.2 + 0.5 + 0.7 + 0.10 + 0.14 + 0.25 + 0.35 + 0.47 + 0.50 + 0.70 + 0.94 + 0.175 + 0.235 + 0.329 + 0.350 + 0.470 + 0.658 + 0.1175 + 0.1645 + 0.2350 + 0.3290 + 0.8225 + 0.16450 = 9; see A276465.
%C A276466 No other term like 16450 up to 4*10^11. - _Giovanni Resta_, Apr 03 2019
%H A276466 Chai Wah Wu, <a href="/A276466/b276466.txt">Table of n, a(n) for n = 1..10000</a>
%F A276466 a(n) = (Sum_{d | n} 0.d) * A276467(n).
%e A276466 For n=12; Sum_{d | 12} 0.d = 0.1 + 0.2 + 0.3 + 0.4 + 0.6 + 0.12 = 1.72 = 172/100 = 43/25; a(12) = 43.
%t A276466 Table[Numerator@ Total@ (#*1/10^(1 + Floor@ Log10@ #)) &@ Divisors@ n, {n, 65}] (* _Michael De Vlieger_, Sep 04 2016 *)
%o A276466 (Magma) [Numerator(&+[d / (10^(#Intseq(d))): d in Divisors(n)]): n in [1..1000]]
%o A276466 (Python)
%o A276466 from fractions import Fraction
%o A276466 from sympy import divisors
%o A276466 def A276466(n):
%o A276466     return sum(Fraction(d,10**len(str(d))) for d in divisors(n)).numerator # _Chai Wah Wu_, Sep 05 2016
%o A276466 (PARI) a(n) = numerator(sumdiv(n, d, d/10^(#Str(d)))); \\ _Michel Marcus_, Mar 29 2019
%Y A276466 Cf. A276465, A276467 (denominator).
%Y A276466 Cf. A078267 and A078268 (both for 0.d).
%K A276466 nonn,base
%O A276466 1,2
%A A276466 _Jaroslav Krizek_, Sep 04 2016