A276479 - OEIS

%I #19 Sep 08 2022 08:46:17

%S 0,0,0,0,0,1,0,1,1,0,0,1,0,1,1,1,0,2,0,1,1,0,0,2,0,0,1,1,0,2,0,1,0,0,

%T 1,3,0,0,0,2,0,2,0,1,2,0,0,3,1,1,1,1,0,3,1,3,1,1,0,3,0,1,2,2,1,2,0,1,

%U 1,2,0,4,0,1,2,2,1,2,0,3,2,1,0,4,1,1,1

%N a(n) = floor(Sum_{d|n} 0.d).

%C Here 0.d means the decimal fraction obtained by writing d after the decimal point, e.g. 0.12 = 12/100 = 3/25.

%C The first few values of Sum_{d|n} 0.d 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 See A276480(n) = the smallest number k such that floor(Sum_{d|k} 0.d) = n.

%H Jaroslav Krizek, <a href="/A276479/b276479.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = floor(A276466(n)/A276467(n)).

%e For n=12: a(12) = floor(Sum_{d|12} 0.d) = floor(0.1 + 0.2 + 0.3 + 0.4 + 0.6 + 0.12 = 0.72) = floor(172/100) = floor(43/25)  = 1.

%t Table[Floor@ Total@ (#*1/10^(1 + Floor@ Log10@ #)) &@ Divisors@ n, {n, 120}] (* _Michael De Vlieger_, Sep 06 2016 *)

%o (Magma) [Floor(&+[d / (10^(#Intseq(d))): d in Divisors(n)]): n in [1..1000]]

%o (PARI) a(n) = floor(sumdiv(n, d, d/10^(#Str(d)))); \\ _Michel Marcus_, Sep 05 2016

%o (Python 3)

%o from fractions import Fraction

%o from sympy import divisors

%o def A276479(n):

%o     return sum(Fraction(d,10**len(str(d))) for d in divisors(n)).__floor__() # _Chai Wah Wu_, Sep 08 2016

%Y Cf. A276466, A276467, A276480.

%K nonn,base

%O 1,18

%A _Jaroslav Krizek_, Sep 05 2016