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 A025550 a(n) = ( 1/1 + 1/3 + 1/5 + ... + 1/(2*n-1) )*LCM(1, 3, 5, ..., 2*n-1). 12
 1, 4, 23, 176, 563, 6508, 88069, 91072, 1593269, 31037876, 31730711, 744355888, 3788707301, 11552032628, 340028535787, 10686452707072, 10823198495797, 10952130239452, 409741429887649, 414022624965424, 17141894231615609, 743947082888833412, 750488463554668427 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Or, numerator of 1/1 + 1/3 + ... + 1/(2n-1) up to a(38). Following similar remark by T. D. Noe in A025547, this coincides with f(n) = numerator of 1 + 1/3 + 1/5 + 1/7 + ... + 1/(2n-1) iff n <= 38. But a(39) = 18048708369314455836683437302413, f(39) = 1640791669937677803334857936583. Note that f(n) = numerator(digamma(n+1/2)/2 + log(2) + euler_gamma/2). - Paul Barry, Aug 19 2005 [See A350669(n-1).] LINKS Georg Fischer, Table of n, a(n) for n = 1..200 (first 39 terms from Jean-François Alcover) Eric Weisstein's World of Mathematics, Jeep Problem MAPLE a:= n-> (f-> add(1/p, p=f)*ilcm(f[]))([2*i-1\$i=1..n]): seq(a(n), n=1..40); # Alois P. Heinz, Apr 16 2015 MATHEMATICA Table[(Total[1/Range[1, 2n-1, 2]])LCM@@Range[1, 2n-1, 2], {n, 30}] (* Harvey P. Dale, Sep 09 2020 *) PROG (Haskell) a025550 n = numerator \$ sum \$ map (1 %) \$ take n [1, 3 ..] -- Reinhard Zumkeller, Jan 22 2012 (PARI) a(n)=my(v=vector(n, i, 2*i-1)); sum(i=1, #v, 1/v[i])*lcm(v) \\ Charles R Greathouse IV, Feb 28 2013 (Magma) [&+[1/d: d in i]*Lcm(i) where i is [1..2*n-1 by 2]: n in [1..21]]; // Bruno Berselli, Apr 16 2015 CROSSREFS Cf. A025547, A075135, A002428, A350669. Sequence in context: A127131 A083355 A141763 * A350669 A067545 A004041 Adjacent sequences: A025547 A025548 A025549 * A025551 A025552 A025553 KEYWORD nonn,easy,nice,frac AUTHOR Clark Kimberling EXTENSIONS Value of a(39) corrected by Jean-François Alcover, Apr 16 2015 STATUS approved

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Last modified September 29 02:45 EDT 2023. Contains 365749 sequences. (Running on oeis4.)