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 A227912 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]. 1
 0, 0, 2, 3, 9, 4, 14, 14, 19, 28, 24, 29, 41, 51, 54, 49, 67, 74, 89, 87, 99, 110, 120, 125, 142, 154, 169, 178, 180, 211, 197, 223, 262, 261, 285, 270, 299, 323, 342, 371, 359, 374, 422, 434, 477, 454, 478, 493, 538, 566, 555, 628, 606, 663, 666, 676, 716 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS EXAMPLE a(6) = 4, only k = 4 satisfies the condition frac(6/k) is an element of [1/4, 3/4]. PROG (JavaScript) for (i=1; i<50; i++) { c=0; for (j=1; j<=i; j++) { v=Math.floor(i/j); if (i/j-v>=0.25 && i/j-v<=0.75) c+=j; } document.write(c+", "); ; } CROSSREFS Cf. A227913. Sequence in context: A242812 A089206 A249824 * A229212 A210586 A202017 Adjacent sequences:  A227909 A227910 A227911 * A227913 A227914 A227915 KEYWORD nonn AUTHOR Jon Perry, Oct 13 2013 STATUS approved

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Last modified October 16 12:00 EDT 2019. Contains 328056 sequences. (Running on oeis4.)