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 A296358 Denominator of the sum of the reciprocals of the first n composite numbers. 10
 4, 12, 24, 72, 360, 360, 2520, 504, 1008, 336, 1680, 1680, 18480, 18480, 92400, 1201200, 10810800, 10810800, 10810800, 21621600, 21621600, 367567200, 52509600, 52509600, 997682400, 997682400, 997682400, 6983776800, 6983776800, 6983776800 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Same as A282512 without the initial 1. LINKS FORMULA Gerry Felderman (Personal communication, Dec 15 2017) observes that Sum_{k=1..n} 1/composite(k) (= A250133(n)/A296358(n)) ~ log(n) - loglog(n) ~ log pi(n) as n -> oo. EXAMPLE 1/4, 5/12, 13/24, 47/72, 271/360, 301/360, 2287/2520, 491/504, 1045/1008, 367/336, 1919/1680, 1999/1680, 22829/18480, ... = A250133/A296358 MATHEMATICA Accumulate[1/Select[Range[100], CompositeQ]]//Denominator (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Oct 19 2018 *) CROSSREFS Numerators are in A250133. The following fractions are all related to each other: Sum 1/n: A001008/A002805, Sum 1/prime(n): A024451/A002110 and A106830/A034386, Sum 1/nonprime(n): A282511/A282512, Sum 1/composite(n): A250133/A296358. Sequence in context: A216244 A215223 A318610 * A282512 A025543 A064354 Adjacent sequences:  A296355 A296356 A296357 * A296359 A296360 A296361 KEYWORD nonn,frac AUTHOR N. J. A. Sloane, Dec 15 2017 STATUS approved

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Last modified July 24 02:53 EDT 2019. Contains 325289 sequences. (Running on oeis4.)