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%I #25 Oct 21 2013 12:40:16
%S 0,0,2,3,9,4,14,14,19,28,24,29,41,51,54,49,67,74,89,87,99,110,120,125,
%T 142,154,169,178,180,211,197,223,262,261,285,270,299,323,342,371,359,
%U 374,422,434,477,454,478,493,538,566,555,628,606,663,666,676,716
%N Sum of all k from {1,...,n} such that the fractional part of n/k is contained in the closed interval [1/4, 3/4].
%e a(6) = 4, only k = 4 satisfies the condition frac(6/k) is an element of [1/4, 3/4].
%o (JavaScript)
%o for (i=1;i<50;i++) {
%o c=0;
%o for (j=1;j<=i;j++) {
%o v=Math.floor(i/j);
%o if (i/j-v>=0.25 && i/j-v<=0.75) c+=j;
%o }
%o document.write(c+", ");
%o ;
%o }
%Y Cf. A227913.
%K nonn
%O 1,3
%A _Jon Perry_, Oct 13 2013