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A275626 Denominator of Sum_{k=1..n} 0.k. 3

%I

%S 10,10,5,1,2,10,5,5,2,5,100,100,25,10,4,100,50,25,20,20,25,50,100,20,

%T 10,25,100,100,5,10,100,100,50,1,20,100,25,50,20,4,50,25,100,20,5,50,

%U 100,100,10,5,100,100,25,10,20,100,50,25,4,20,25,50,100,20,2,25,100,100,5,10,100,100,50

%N Denominator of Sum_{k=1..n} 0.k.

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

%H Alois P. Heinz, <a href="/A275626/b275626.txt">Table of n, a(n) for n = 1..20000</a>

%e The first few values of Sum{k=1..n} 0.k are:

%e 1/10, 3/10, 3/5, 1, 3/2, 21/10, 14/5, 18/5, 9/2, 23/5, 471/100, 483/100, 124/25, 51/10, 21/4, 541/100, 279/50, 144/25, 119/20, 123/20, 159/25, 329/50, 681/100, 141/20, 73/10, 189/25, ...

%p b:= proc(n) option remember;

%p n/10^length(n)+`if`(n<2, 0, b(n-1))

%p end:

%p a:= n-> denom(b(n)):

%p seq(a(n), n=1..100); # _Alois P. Heinz_, Aug 16 2016

%Y Cf. A275626, A054464 (when a(n) = 1), A275623, A275624.

%K nonn,base,frac

%O 1,1

%A _N. J. A. Sloane_, Aug 07 2016

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Last modified January 23 03:15 EST 2022. Contains 350504 sequences. (Running on oeis4.)