cp's OEIS Frontend

A276651 a(n) = numerator of Sum_{p|n} 0.d where p runs through the prime divisors of n.

%I A276651 #18 Sep 08 2022 08:46:17
%S A276651 1,3,1,1,1,7,1,3,7,11,1,13,9,4,1,17,1,19,7,1,31,23,1,1,33,3,9,29,1,31,
%T A276651 1,41,37,6,1,37,39,43,7,41,6,43,31,4,43,47,1,7,7,47,33,53,1,61,9,49,
%U A276651 49,59,1,61,51,1,1,63,61,67,37,53,7,71,1,73,57,4,39
%N A276651 a(n) = numerator of Sum_{p|n} 0.d where p runs through the prime divisors of n.
%C A276651 Here 0.d means the decimal fraction obtained by writing d after the decimal point, e.g., 0.11 = 11/100.
%C A276651 The first few values of Sum_{p|n} 0.d are: 1/5, 3/10, 1/5, 1/2, 1/2, 7/10, 1/5, 3/10, 7/10, ...
%C A276651 See A276655 - numbers n such that Sum_{p|n} 0.d is an integer.
%H A276651 Jaroslav Krizek, <a href="/A276651/b276651.txt">Table of n, a(n) for n = 2..1000</a>
%F A276651 a(n) = (Sum_{p|n} 0.d) * A276652(n) where p = prime divisors of n.
%e A276651 For n=12; Sum_{p|12} 0.d = 0.2 + 0.3 = 0.5 = 5/10 = 1/2; a(12) = 1.
%t A276651 Numerator[Table[f = FactorInteger[i][[All, 1]];
%t A276651 Total[f*10^-IntegerLength[f]], {i, 2, 76}]] (* _Robert Price_, Sep 20 2019 *)
%o A276651 (Magma) [Numerator(&+[d/(10^(#Intseq(d))): d in PrimeDivisors(n)]): n in [2..1000]]
%Y A276651 Cf. A276652, A276653, A276654, A276655, A276513.
%K A276651 nonn,base,frac
%O A276651 2,2
%A A276651 _Jaroslav Krizek_, Sep 10 2016